Ferri's Best Test: A Practical Guide to Clinical Laboratory Medicine and Diagnostic Imaging (Ferri's Medical Solutions) 0323812899, 9780323812894

Citation preview

Any screen. Any time. Anywhere. Activate the eBook version of this title at no additional charge. rge.

Elsevier eBooks for Practicing Clinicians gives you the power to browse and search content, view enhanced images, highlight and

Unlock your eBook today. 1. Visit expertconsult.inkling.com/redeem 2. Scratch box below to reveal your code 3. Type code into “Enter Code” box 4. Click “Redeem” 5. Log in or Sign up 6. Go to “My Library”

It’s that easy! Place Peel Off Sticker Here

For technical assistance: email [email protected] call 1-800-401-9962 (inside the US) call +1-314-447-8300 (outside the US) Use of the current edition of the electronic version of this book (eBook) is subject to the terms of the nontransferable, limited license granted on expertconsult.inkling.com. Access to the eBook is limited to the first individual who redeems the PIN, located on the inside cover of this book, at expertconsult. inkling.com and may not be transferred to another party by resale, lending, or other means. 2020_PC

FERRI’S BEST TEST

This page intentionally left blank

     

FERRI’S BEST TEST A Practical Guide to Clinical Laboratory Medicine and Diagnostic Imaging EDITION

5

FRED F. FERRI, MD, FACP Clinical Professor of Medicine The Warren Alpert Medical School of Brown University Providence, Rhode Island

Elsevier 1600 John F. Kennedy Blvd. Ste 1800 Philadelphia, PA 19103-2899 FERRI’S BEST TEST: A PRACTICAL GUIDE TO CLINICAL LABORATORY MEDICINE AND DIAGNOSTIC IMAGING, FIFTH EDITION ISBN: 978-0-323-81289-4 Copyright © 2023 by Elsevier Inc. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under ­copyright by the Publisher (other than as may be noted herein). Notice Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds or experiments described herein. Because of rapid advances in the medical sciences, in particular, independent verification of diagnoses and drug dosages should be made. To the fullest extent of the law, no responsibility is assumed by Elsevier, authors, editors or contributors for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. Previous editions copyrighted 2019, 2015, 2010, 2004. International Standard Book Number: 978-0-323-812894

Content Strategist: Marybeth Thiel Content Development Manager: Meghan Andress Content Development Specialist: Nicole Congleton Publishing Services Manager: Julie Eddy Senior Project Manager: Jodi Willard Design Direction: Bridget Hoette Printed in the United States of America Last digit is the print number: 9 8 7 6 5 4 3 2 1

Preface This book is intended to be a practical and concise guide to clinical laboratory medicine and diagnostic imaging. It is designed for use by medical students, interns, residents, practicing physicians, and other health care personnel who deal with laboratory testing and diagnostic imaging in their daily work. As technology evolves, physicians and other health care professionals are faced with a constantly changing armamentarium of diagnostic imaging and laboratory tests to supplement their clinical skills in arriving at a correct diagnosis. In addition, with the advent of managed care, it is increasingly important for physicians to practice costeffective medicine. The aim of this book is to be a practical reference for ordering tests, whether they are laboratory tests or diagnostic imaging studies. As such, it is unique in medical publishing. This manual is divided into three main sections: clinical laboratory testing, diagnostic imaging, and diagnostic algorithms. With the fifth edition, appendixes have been expanded to include electrocardiography and pulmonary function testing. Section I deals with common diagnostic imaging tests. Each test is approached with the following format: Indications, Strengths, Weaknesses, and Comments. The approximate cost of each test is also indicated. In this edition, we have added several new diagnostic modalities, including cardiac computed tomography angiography, computed tomography perfusion imaging, and cardiac catheterization and angiography. Several new comparison tables and illustrations have also been added to this section. Section II describes over 300 laboratory tests. The fifth edition features several new laboratory tests, tables, and illustrations. Each test in this section is approached with the following format: • Laboratory test • Normal range in adult patients • Common abnormalities (e.g., positive test, increased or decreased value) • Causes of abnormal result Section III includes the diagnostic modalities (imaging and laboratory tests) and algorithms of common diseases and disorders. Several algorithms, tables, and illustrations have been added to this edition. I hope that this unique approach will simplify the diagnostic testing labyrinth and lead the readers of this manual to choose the best test to complement their clinical skills. However, it is important to remember that laboratory tests and x-rays do not make diagnoses—doctors and health care professionals do. As such, any laboratory or radiographic results should be integrated with the complete clinical picture to arrive at a diagnosis. Fred F. Ferri, MD, FACP Clinical Professor of Medicine The Warren Alpert Medical School of Brown University Providence, Rhode Island

v

This page intentionally left blank

     

Acknowledgments I extend a special thank you to the authors and contributors of the following texts, who have lent multiple images, illustrations, and text material to this edition: Bennett JE, et al. Mandell, Douglas, and Bennett’s principles and practice of infectious diseases, ed 9, Philadelphia, 2019, Elsevier. Bolognia J. Dermatology, ed 4, Philadelphia, 2018, Elsevier. Boxt LM, Abbara S. The requisites: cardiac imaging, ed 4, Philadelphia, 2016, Elsevier. Cameron P, et al. Textbook of adult emergency medicine, ed 5, Philadelphia, 2019, Elsevier. Disaia, PJ, et al. Clinical gynecologic oncology, ed 9, Philadelphia, 2018, Elsevier. Feldman M, Friedman LS, Brandt LJ. Sleisenger and Fortran’s gastrointestinal and liver disease, ed 10, Philadelphia, 2016, Elsevier. Goldman L, Shafer AI. Goldman-Cecil medicine, ed 26, Philadelphia, 2019, Elsevier. Grant, LA. Grainger & Allison’s diagnostic radiology essentials, ed 2, Philadelphia, 2019, Elsevier. Marx JA, et al. Rosen’s emergency medicine, ed 8, Philadelphia, 2014, Saunders. Mason RJ et al. Murray and Nadel’s textbook of respiratory medicine, ed 5, Philadelphia, 2010, Elsevier. McPherson RA, Pincus MR. Henry’s clinical diagnosis and management by laboratory methods, ed 23, Philadelphia, 2017, Elsevier. Melmed S, et al. Williams textbook of endocrinology, ed 14, Philadelphia, 2019, Elsevier. Ryan ET, at al. Hunter’s tropical medicine and emerging infectious diseases, ed 10, Philadelphia, 2019, Elsevier. Sellke FW, del Nido PJ, Swanson SJ. Sabiston and Spencer surgery of the chest, ed 9, Philadelphia, 2016, Elsevier. Soto JA, Lucey BC. Emergency radiology: the requisites, ed 2, Philadelphia, 2017, Elsevier. Fred F. Ferri, MD, FACP Clinical Professor of Medicine The Warren Alpert Medical School of Brown University Providence, Rhode Island

vii

This page intentionally left blank

     

Contents Section I Diagnostic Imaging,  1 . Abdominal and Gastrointestinal (GI) Imaging,  4 A 1. Abdominal Film, Plain (Kidney, Ureter, and Bladder [KUB]),  4 2. Barium Enema (BE),  5 3. Barium Swallow (Esophagram),  7 4. Upper GI (UGI) Series,  8 5. Computed Tomographic Colonography (CTC, Virtual Colonoscopy),  9 6. CT Scan of Abdomen and Pelvis,  10 7. CT Enterography,  12 8. CT Enteroclysis,  17 9. Magnetic Resonance Enterography (MRE),  18 10. Cholescintigraphy (Hepatobiliary Iminodiacetic Acid [HIDA] Scan, Diisopropyl Iminodiacetic Acid [DISIDA] Scan),  19 11. Endoscopic Retrograde Cholangiopancreatography (ERCP),  21 12. Percutaneous Biliary Procedures,  22 13. Magnetic Resonance Cholangiopancreatography (MRCP),  23 14. Meckel Scan (Tc-99m Pertechnetate Scintigraphy),  25 15. MRI Scan of Abdomen/Pelvis,  26 16. Small-Bowel Series,  28 17. Tc-99m Sulfur Colloid (Tc-99m SC) Scintigraphy for GI Bleeding,  29 18. Tc-99m-Labeled Red Blood Cell (RBC) Scintigraphy for GI Bleeding,  30 19. Ultrasound of Abdomen,  30 20. Ultrasound of Appendix,  32 21. Ultrasound of Gallbladder and Bile Ducts,  33 22. Ultrasound of Liver,  35 23. Ultrasound of Pancreas,  35 24. Endoscopic Ultrasound (EUS),  39 25. Video Capsule Endoscopy (VCE),  40 26. Transient Elastography (FibroScan),  42 B. Breast Imaging,  42 1. Mammogram,  42 2. Breast Ultrasound,  44 3. MRI of the Breast,  47 C. Cardiac Imaging,  48 1. Stress Echocardiography,  48 2. Cardiovascular Radionuclide Imaging (Thallium, Sestamibi, Dipyridamole [Persantine] Scan), Positron Emission Tomography (PET), Single-Photon Emission Computed Tomography (SPECT),  50 3. Cardiac MRI (CMR),  51 4. Multidetector CT Scan (Non-contrast CT Scan for Coronary Artery Calcium Scoring), 55 5. Transesophageal Echocardiogram (TEE),  58 6. Transthoracic Echocardiography (TTE),  59 7. Intravascular Ultrasound (IVUS),  60 D. Chest Imaging,  66 1. Chest Radiograph,  66 2. CT Scan of Chest,  68 3. MRI Scan of Chest,  73

ix

x

Contents

E. Endocrine Imaging,  74 1. Adrenal Medullary Scintigraphy (Metaiodobenzylguanidine [MIBG] Scan),  74 2. Parathyroid (PTH) Scan,  75 3. Thyroid Scan (Radioiodine Uptake Study),  76 4. Thyroid Ultrasound,  77 F. Genitourinary Imaging,  78 1. Obstetric Ultrasound,  78 2. Pelvic Ultrasound,  78 3. Prostate Ultrasound,  80 4. Renal Ultrasound,  81 5. Scrotal Ultrasound,  82 6. Transvaginal (Endovaginal) Ultrasound,  83 7. Urinary Bladder Ultrasound,  84 8. Hysterosalpingography (HSG),  85 9. Intravenous Pyelography (IVP) and Intravenous Retrograde Pyelography, 86 G. Musculoskeletal and Spinal Cord Imaging,  88 1. Plain X-Ray Films of Skeletal System,  88 2. Bone Densitometry (Dual-Energy X-Ray Absorptiometry [DEXA] Scan), 89 3. MRI Scan of Spine,  90 4. MRI Scan of Shoulder,  93 5. MRI Scan of Hip and Extremities,  94 6. MRI Scan of Pelvis,  95 7. MRI Scan of Knee,  95 8. CT Scan of Spinal Cord,  98 9. Arthrography,  99 10. CT Myelography,  100 11. Nuclear Imaging (Bone Scan, Gallium Scan, White Blood Cell [WBC] Scan),  100 H. Neuroimaging of Brain,  102 1. CT Scan of Brain,  102 2. MRI Scan of Brain,  103 I. Positron Emission Tomography (PET),  107 J. Single-Photon Emission Computed Tomography (SPECT),  109 K. Vascular Imaging,  110 1. Angiography,  110 2. Aorta Ultrasound,  113 3. Arterial Ultrasound,  115 4. Captopril Renal Scan (CRS),  115 5. Carotid Ultrasonography,  116 6. Computed Tomographic Angiography (CTA),  117 7. Cardiac Computed Tomography Angiography,  119 8. Computed Tomography Perfusion (CTP) Imaging,  120 9. Cardiac Catheterization and Angiography,  121 10. Magnetic Resonance Angiography (MRA),  121 11. Magnetic Resonance Direct Thrombus Imaging (MRDTI),  129 12. Pulmonary Angiography,  129 13. Transcranial Doppler,  130 14. Venography,  131 15. Compression Ultrasonography and Venous Doppler Ultrasound,  132 16. Ventilation/Perfusion (V/Q) Lung Scan,  133 L. Oncology,  135 1. Whole-Body Integrated (Dual-Modality) PET-CT,  135 2. Whole-Body MRI,  137 References, 137 

Contents

xi

Section II Laboratory Values and Interpretation of Results, 139 ACE Level,  148 Acetone (Serum or Plasma),  148 Acetylcholine Receptor (AChR) Antibody, 148 Acid Phosphatase (Serum),  148 Acid Serum Test,  148 Activated Clotting Time (ACT),  148 Activated Partial Thromboplastin Time (aPTT), 148 Adrenocorticotropic Hormone (ACTH), 148 Alanine Aminopeptidase,  149 Alanine Aminotransferase (ALT, Formerly Serum Glutamic-Pyruvic Transaminase [SGPT]),  149 Albumin (Serum),  149 Alcohol Dehydrogenase,  149 Aldolase (Serum),  149 Aldosterone (Plasma),  149 Alkaline Phosphatase (Serum),  150 Alpha-1-Antitrypsin (Serum),  151 Alpha-1-Fetoprotein (Serum),  151 ALT, 151 Aluminum (Serum),  151 AMA, 151 Amebiasis Serologic Test,  152 Aminolevulinic Acid (d-ALA) (24-Hour Urine Collection),  152 Ammonia (Serum),  152 Amylase (Serum),  152 Amylase, Urine,  152 Amyloid A Protein (Serum),  152 ANA, 152 Anaplasma Phagocytophilum (HGA), 152 ANCA, 152 Androstenedione (Serum),  153 Angiotensin II,  153 Angiotensin-Converting Enzyme (ACE) Level,  153 ANH, 153 Anion Gap,  153 Anticardiolipin Antibody (ACA),  153 Anticentromere Antibody,  153 Anticoagulant, 154 Antidiuretic Hormone,  154 Anti-DNA, 154 Anti-dsDNA, 155 Antiglobulin Test, Direct,  155 Antiglobulin Test, Indirect,  155 Antiglomerular Basement Antibody, 155 Anti-HCV, 155

Antihistone, 155 Anti-Jo-1, 155 Antimitochondrial Antibody (AMA), 155 Antineutrophil Cytoplasmic Antibody (ANCA), 155 Antinuclear Antibody (ANA),  155 Antiphospholipid Antibody,  156 Anti-RNP Antibody,  156 Anti-Scl-70, 156 Anti-Smith (Anti-Sm) Antibody,  157 Anti-Smooth Muscle Antibody,  157 Antistreptolysin O Titer (Streptozyme, ASLO Titer),  157 Antithrombin III,  157 Apolipoprotein A-1 (Apo A-1),  157 Apolipoprotein B (Apo B),  157 Arterial Blood Gases,  157 Arthrocentesis Fluid,  160 ASLO Titer,  160 Aspartate Aminotransferase (AST, Serum Glutamic Oxaloacetic Transaminase [SGOT]),  160 Atrial Natriuretic Hormone (ANH), 161 Basophil Count,  161 Beta-2 Microglobulin,  161 Bicarbonate, 161 Bile Acid Breath Test,  161 Bile, Urine,  161 Bilirubin, Direct (Conjugated Bilirubin), 162 Bilirubin, Indirect (Unconjugated Bilirubin), 162 Bilirubin, Total,  162 Bilirubin, Urine,  162 Bladder Tumor–Associated Antigen, 162 Bleeding Time (Modified IVY Method), 162 Blood Type,  163 Blood Volume, Total,  165 Bordetella pertussis Serology,  165 BRCA-1, BRCA-2, 165 Breath Hydrogen Test,  165 B-Type Natriuretic Peptide (BNP),  165 BUN, 166 C3, 166 C4, 166 CA 15-3,  166 CA 19-9,  166 CA 27-29,  166 CA 72-4,  166

xii

Contents

CA 125,  166 Calcitonin (Serum),  166 Calcium (Serum),  166 Calcium, Urine,  167 Cancer Antigen 15-3 (CA 15-3),  167 Cancer Antigen 19-9 (CA 19-9),  167 Cancer Antigen 27-29 (CA 27-29),  167 Cancer Antigen 72-4 (CA 72-4),  169 Cancer Antigen 125 (CA-125),  169 Captopril Stimulation Test,  169 Carbamazepine (Tegretol),  169 Carbohydrate Antigen 19-9,  169 Carbon Dioxide, Partial Pressure,  170 Carbon Monoxide,  170 Carboxyhemoglobin (COHb),  170 Cardiac Markers (Serum),  170 Cardiac Troponins,  171 Carcinoembryonic Antigen (CEA),  171 Cardio-CRP, 172 Carotene (Serum),  172 Catecholamines, Urine,  172 CBC, 172 CCK, 172 CCK-PZ, 172 CCP IgG Antibody,  172 CD4 T-Lymphocyte Count (CD4 T-Cells), 172 CD40 Ligand,  173 CEA, 173 Cerebrospinal Fluid (CSF),  173 Ceruloplasmin (Serum),  176 Chlamydia Group Antibody Serologic Test, 176 Chlamydia trachomatis Nucleic Acid Amplification Test (NAAT), 176 Chlamydia trachomatis Polymerase Chain Reaction (PCR),  176 Chloride (Serum),  176 Chloride (Sweat),  177 Chloride, Urine,  177 Cholecystokinin-Pancreozymin (CCK, CCK-PZ), 177 Cholesterol, Low-Density Lipoprotein, 177 Cholesterol, High-Density Lipoprotein, 177 Cholesterol, Total,  177 Chorionic Gonadotropin (hCG), Human (Serum),  177 Chymotrypsin, 178 Circulating Anticoagulant (Antiphospholipid Antibody, Lupus Anticoagulant),  178 CK, 178 Clonidine Suppression Test,  178

Clostridium (Clostridioides) difficile Toxin Assay (Stool),  178 CO, 178 Coagulation Factors,  178 Cold Agglutinins Titer,  180 Complement (C3, C4),  180 Complete Blood Cell (CBC) Count (Normal Values),  181 Conjugated Bilirubin,  182 Coombs, Direct,  182 Coombs, Indirect (Antiglobulin, Indirect), 182 Copper (Serum),  183 Copper, Urine,  183 Coronavirus, 183 Corticotropin-Releasing Hormone (CRH) Stimulation Test,  183 Cortisol (Plasma),  183 COVID-19 (SARS-CoV-2),  183 C-Peptide, 184 CPK, 184 C-Reactive Protein (CRP),  184 Creatinine Clearance,  184 Creatine Kinase (CK), Creatine Phosphokinase (CPK),  185 Creatine Kinase Isoenzymes,  185 Creatinine (Serum),  186 Creatinine, Urine,  186 Cryoglobulins (Serum),  186 Cryptosporidium Antigen by Enzyme Immunoassay (EIA) (Stool),  186 CSF, 186 Cystatin C,  186 Cystic Fibrosis Polymerase Chain Reaction (PCR),  187 Cytomegalovirus by Polymerase Chain Reaction (PCR),  187 DAT, 187 d-Dimer, 187 Dehydroepiandrosterone Sulfate,  187 Deoxycorticosterone (11-Deoxycorticosterone, DOC), Serum, 187 Dexamethasone Suppression Test, Overnight, 188 Digoxin, 188 Dihydrotestosterone, Serum, Urine, 188 Dilantin, 189 Direct Antiglobulin Test (DAT, Coombs Test Direct),  189 Disaccharide Absorption Tests,  190 DOC, 190 Donath-Landsteiner (D-L) Test for Paroxysmal Cold Hemoglobinuria, 190

Contents Dopamine, 190 d-Xylose Absorption Test,  190 Electrolytes, Urine,  190 Electrophoresis, Hemoglobin,  190 Electrophoresis, Protein,  190 ENA Complex,  190 Endomysial Antibodies,  191 Eosinophil Count,  191 Epinephrine, Plasma,  191 Epstein-Barr Virus (EBV) Serology, 191 Erythrocyte Sedimentation Rate (ESR) (Westergren), 192 Erythropoietin (EP),  192 Estradiol (Serum),  192 Estrogens, Total,  192 Ethanol (Blood),  193 Extractable Nuclear Antigen (ENA Complex, Anti-RNP Antibody, Anti-SM, Anti-Smith),  193 Factor V Leiden,  193 FDP, 193 FENA, 193 Fecal FAT, Qualitative,  193 Fecal FAT, Quantitative (72-Hour Collection), 193 Fecal Globin Immunochemical Test, 193 Ferritin (Serum),  194 Fibrin Degradation Product (FDP), 194 Fibrinogen, 194 5-Hydroxyindole-Acetic Acid, Urine, 194 5′ Nucleotidase,  194 Fluorescent Treponemal Antibody,  194 Folate (Folic Acid),  194 Follicle-Stimulating Hormone (FSH), 194 Fractional Excretion of Sodium (FENA), 195 Free T4, 195 Free Thyroxine Index,  195 FSH, 195 FTA-ABS (Serum),  196 Furosemide Stimulation Test,  196 Gamma-Glutamyl Transferase (GGT), 196 Gastrin (Serum),  196 Gastrin Stimulation Test,  196 Gliadin Antibodies, Immunoglobulin (Ig) A and IgG,  196 Glomerular Basement Membrane Antibody, 196 Glomerular Filtration Rate (GFR),  196 Glucagon, 197

xiii

Glucose, Fasting,  198 Glucose, Postprandial,  198 Glucose Tolerance Test,  198 Glucose-6-Phosphate Dehydrogenase (G6PD) Screen (Blood),  198 γ-Glutamyl Transferase (GGT),  198 Glycated (Glycosylated) Hemoglobin (HbA1c), 198 Glycohemoglobin, 199 Growth Hormone,  199 Growth Hormone–Releasing Hormone (GHRH), 199 Growth Hormone Suppression Test (After Glucose),  199 Ham Test (Acid Serum Test),  199 Haptoglobin (Serum),  199 HbA1c, 199 hCG Tumor Marker,  199 HDL, 200 Helicobacter pylori (Serology, Stool Antigen), 200 Hematocrit, 200 Hemoglobin, 200 Hemoglobin (Hb) Electrophoresis,  201 Hemoglobin, Glycated,  201 Hemoglobin, Glycosylated,  201 Hemoglobin H,  202 Hemoglobin, Urine,  202 Hemosiderin, Urine,  202 Heparin-Induced Thrombocytopenia Antibodies, 202 Hepatitis A Antibody,  203 Hepatitis B Core Antibody,  203 Hepatitis B DNA,  203 Hepatitis Be Antigen (HBeAg) and Antibody, 204 Hepatitis B Surface Antibody,  204 Hepatitis B Surface Antigen (HBsAg), 204 Hepatitis C Antibody (Anti-HCV),  204 Hepatitis C Genotype,  204 Hepatitis C RNA,  205 Hepatitis D Antigen and Antibody,  205 HER-2/neu, 206 Herpes Simplex Virus (HSV),  206 Heterophil Antibody,  206 HFE Screen for Hereditary Hemochromatosis, 207 High-Density Lipoprotein (HDL) Cholesterol, 207 Homocysteine, Plasma,  207 Hs-CRP, 208 HSV, 208 Human Chorionic Gonadotropins (hCG), 208 Human Herpes Virus 8 (HHV8),  208

xiv

Contents

Human Immunodeficiency Virus Antibody, Type 1 (HIV-1),  208 Human Papilloma Virus (HPV),  209 Huntington Disease Polymerase Chain Reaction (PCR),  209 17-Hydroxyprogesterone, 210 Immune Complex Assay,  210 Immunoglobulin (Ig),  210 Influenza A and B Tests,  211 INR, 211 Insulin Autoantibodies,  211 Insulin, Free,  211 Insulin-Like Growth Factor 1 (IGF-1), Serum, 211 Insulin-Like Growth Factor II,  212 International Normalized Ratio (INR), 212 Intrinsic Factor Antibodies,  212 Iron-Binding Capacity (Total IronBinding Capacity [TIBC]),  212 Iron Saturation (% Transferrin Saturation), 212 Iron, Serum,  213 Lactate (Blood),  213 Lactate Dehydrogenase (LDH),  213 Lactate Dehydrogenase (LDH) Isoenzymes, 213 Lactose Tolerance Test (Serum),  213 LAP Score,  213 LDH, 214 LDL, 214 Lead, 214 Legionella pneumophila Polymerase Chain Reaction (PCR),  214 Legionella Titer,  215 Leukocyte Alkaline Phosphatase (LAP), 215 LH, 215 Lipase, 215 Lipoprotein (A),  215 Lipoprotein Cholesterol, Low Density, 215 Lipoprotein Cholesterol, High Density, 215 Liver Kidney Microsome Type 1 (LKM1) Antibodies,  215 Low-Density Lipoprotein (LDL) Cholesterol, 216 Lupus Anticoagulant (LA) Test,  216 Luteinizing Hormone (LH), Blood, 216 Lymphocytes, 216 Magnesium (Serum),  216 Mean Corpuscular Volume (MCV),  217 Metanephrines, Urine,  217 Methylmalonic Acid, Serum,  217

Mitochondrial Antibody (Antimitochondrial Antibody [AMA]), 217 Monocyte Count,  218 Mycoplasma pneumoniae Polymerase Chain Reaction (PCR),  218 Myelin Basic Protein, Cerebrospinal Fluid, 218 Myoglobin, Urine,  218 Natriuretic Peptide,  218 Neisseria gonorrhoeae Nucleic Acid Amplification Test (NAAT),  219 Neisseria gonorrhoeae Polymerase Chain Reaction (PCR),  219 Neutrophil Count,  219 Norepinephrine, 219 Osmolality, Serum,  219 Osmolality, Urine,  219 Osmotic Fragility Test,  219 Paracentesis Fluid,  220 Parathyroid Hormone,  221 Parietal Cell Antibodies,  221 Partial Thromboplastin Time (PTT), Activated Partial Thromboplastin Time (aPTT),  221 Pepsinogen I,  222 PFA, 222 pH, Blood,  222 Phenobarbital, 222 Phenytoin (Dilantin),  222 Phosphatase, Acid,  222 Phosphatase, Alkaline,  222 Phosphate (Serum),  222 pH, Urine,  223 Plasminogen, 223 Platelet Aggregation,  223 Platelet Antibodies,  223 Platelet Count,  224 Platelet Function Analysis (PFA) 100 Assay, 224 Potassium (Serum),  225 Potassium, Urine,  226 Progesterone, Serum,  226 Prolactin, 226 Prostate-Specific Antigen (PSA),  227 Prostatic Acid Phosphatase,  227 Protein (Serum),  227 Protein C Assay,  227 Protein Electrophoresis (Serum),  227 Protein S Assay,  229 Prothrombin Time (PT),  229 Protoporphyrin (Free Erythrocyte), 229 PSA, 229 PT, 229 PTT, 230

Contents Pulse Oximetry,  230 QuantiFERON-TB, 230 Rapid Plasma Reagin,  230 RDW, 230 Red Blood Cell Count,  230 Red Blood Cell Distribution Width (RDW), 231 Red Blood Cell Folate,  231 Red Blood Cell Mass (Volume),  231 Renin (Serum),  231 Respiratory Syncytial Virus (RSV) Screen, 231 Reticulocyte Count,  232 Rheumatoid Factor,  232 RNP, 232 Rotavirus Serology,  232 RPR, 232 SARS-CoV-2, 233 SARS-CoV-2 Antibodies,  233 Sedimentation Rate,  234 Semen Analysis,  234 SGOT, 234 SGPT, 234 Sickle Cell Test,  234 Smooth Muscle Antibody,  234 Sodium (Serum),  234 Streptozyme, 235 Sucrose Hemolysis Test (Sugar Water Test), 235 Sudan III Stain (Qualitative Screening for Fecal Fat),  236 T3 (Triiodothyronine),  236 T3 Resin Uptake (T3RU), 236 T4, Serum T4, and Free (Free Thyroxine), 236 Serum Free T4, 236 Tegretol, 237 Testosterone, 237 Theophylline, 237 Thiamine, 237 Thoracentesis Fluid,  238 Thrombin Time (TT),  238 Thyroglobulin, 238 Thyroid-Binding Globulin (TBG),  239 Thyroid Microsomal Antibodies,  239 Thyroid-Stimulating Hormone (TSH), 239 Thyrotropin (Thyroid-Stimulating Hormone [TSH]) Receptor Antibodies, 240 Thyrotropin-Releasing Hormone (TRH) Stimulation Test,  240 TIBC, 240 Tissue Transglutaminase Antibody, 241 Transferrin, 241

xv

Triglycerides, 241 Triiodothyronine, 241 Troponins, Serum,  241 TSH, 241 TT, 242 Unconjugated Bilirubin,  242 Urea Nitrogen,  242 Uric Acid (Serum),  242 Urinalysis, 243 Urine Amylase,  245 Urine Bile,  245 Urine Calcium,  245 Urine cAMP,  245 Urine Catecholamines,  245 Urine Chloride,  246 Urine Copper,  246 Urine Cortisol, Free,  246 Urine Creatinine (24-Hour),  246 Urine Crystals,  246 Urine Eosinophils,  246 Urine 5-Hydroxyindole-Acetic Acid (Urine 5-HIAA),  246 Urine Glucose (Qualitative),  246 Urine Hemoglobin, Free,  246 Urine Hemosiderin,  247 Urine Indican,  247 Urine Ketones (Semiquantitative),  247 Urine Metanephrines,  247 Urine Myoglobin,  247 Urine Nitrite,  247 Urine Occult Blood,  247 Urine Osmolality,  247 Urine pH,  248 Urine Phosphate,  248 Urine Potassium,  248 Urine Protein (Quantitative),  248 Urine Sodium (Quantitative),  248 Urine Specific Gravity,  248 Urine Vanillylmandelic Acid (VMA), 249 Varicella Zoster Virus (VZV) Serologic Testing, 249 Vasoactive Intestinal Peptide (VIP),  249 Venereal Disease Research Laboratories (VDRL), 249 VIP, 250 Viscosity (Serum),  250 Vitamin B12, 250 Vitamin D, 1, 25 Dihydroxy Calciferol, Vitamin D 25(OH) D (25-Hydroxyvitamin D),  251 Vitamin K,  251 von Willebrand Factor,  252 WBCs, 252 Westergren, 252 White Blood Cell Count,  252 

xvi

Contents

Section III Diseases and Disorders,  253 Acronyms, 257 1. Abdominal Abscess,  259 2. Abdominal Aortic Aneurysm,  261 3. Abdominal Pain,  262 4. Achalasia,  264 5. Acid-Base Disorders,  265 6. Acute Kidney Injury,  268 7. Addison Disease (Adrenal Insufficiency), 269 8. Adrenal Incidentaloma,  270 9. Adrenal Mass,  272 10. Alkaline Phosphatase Elevation, 274 11. ALT/AST Elevation,  275 12. Amenorrhea, Primary,  276 13. Amenorrhea, Secondary,  277 14. Anemia, Macrocytic,  278 15. Anemia, Microcytic,  279 16. Anisocoria,  280 17. Antinuclear Antibody (ANA)– Positive, 282 18. Aortic Dissection,  284 19. Appendicitis,  286 20. Ascites,  287 21. Avascular Necrosis,  290 22. Back Pain, Acute, Lumbosacral (LS) Area, 291 23. Bilirubin Elevation,  293 24. Bleeding Disorder, Congenital, 296 25. Brain Abscess,  297 26. Breast Mass,  298 27. Carcinoid Syndrome,  300 28. Cardiomegaly on Chest Radiograph, 301 29. Chest Pain,  302 30. Cholangitis,  305 31. Cholecystitis,  307 32. Cholelithiasis,  309 33. Chronic Cough,  310 34. Chronic Obstructive Pulmonary Disease, 312 35. Colon Ischemia,  313 36. Complex Regional Pain Syndrome (Reflex Sympathetic Dystrophy [RSD]), 314 37. Constipation,  315 38. Creatinine Phosphokinase (CPK) Elevation, 316 39. Cushing Syndrome,  317 40. Deep Vein Thrombosis (DVT),  321 41. Delayed Puberty,  323 42. Delirium,  324

43. Diarrhea,  325 44. Disseminated Intravascular Coagulation (DIC),  328 45. Diverticulitis,  329 46. Dyspepsia,  330 47. Dyspnea,  331 48. Dysuria,  332 49. Ectopic Pregnancy,  333 50. Edema, Lower Extremity,  335 51. Endocarditis, Infective,  337 52. Endometriosis,  339 53. Epiglottitis,  340 54. Fatigue,  342 55. Fever and Neutropenia,  343 56. Fever of Undetermined Origin (FUO), 344 57. Galactorrhea,  345 58. Genital Lesions/Ulcers,  347 59. Granulomatosis With Polyangiitis (Wegener Granulomatosis),  348 60. Goiter,  349 61. Gynecomastia,  350 62. Hearing Loss,  351 63. Hematochezia,  352 64. Hematuria,  353 65. Hemochromatosis,  356 66. Hemoptysis,  357 67. Hepatomegaly,  358 68. Hirsutism,  359 69. Hyperaldosteronism,  359 70. Hypercalcemia,  361 71. Hyperkalemia,  362 72. Hypermagnesemia,  363 73. Hypernatremia,  364 74. Hyperphosphatemia,  365 75. Hyperthyroidism,  366 76. Hypocalcemia,  367 77. Hypoglycemia,  368 78. Hypogonadism,  369 79. Hypokalemia,  371 80. Hypomagnesemia,  373 81. Hyponatremia,  375 82. Hypophosphatemia,  376 83. Hypothyroidism,  376 84. Immunodeficiency,  378 85. Infectious Diarrhea,  381 86. Infertility,  382 87. Jaundice,  384 88. Joint Effusion,  386 89. Liver Function Test Elevations, 387 90. Liver Mass,  389

Contents 91. Lymphadenopathy, Generalized, 390 92. Malabsorption, Suspected,  392 93. Meningioma,  395 94. Mesenteric Ischemia,  396 95. Mesothelioma,  397 96. Metabolic Acidosis,  398 97. Metabolic Alkalosis,  399 98. Microcytosis,  400 99. Multiple Myeloma,  401 100. Multiple Sclerosis,  402 101. Myalgias,  403 102. Muscle Weakness,  404 103. Neck Mass,  406 104. Neck Pain,  407 105. Neuropathy,  408 106. Neutropenia,  409 107. Osteomyelitis,  411 108. Pancreatic Mass,  412 109. Pancreatitis, Acute,  414 110. Parapharyngeal Abscess,  416 111. Pelvic Mass,  417 112. Pelvic Pain, Female Patient,  418 113. Peripheral Arterial Disease (PAD), 420 114. Pheochromocytoma,  422 115. Pituitary Adenoma,  423 116. Pleural Effusion,  425 117. Polyarteritis Nodosa,  427 118. Polycythemia,  428 119. Portal Vein Thrombosis,  429 120. Precocious Puberty,  431 121. Proteinuria,  433 122. Pruritus, Generalized,  434 123. Pulmonary Embolism,  436 124. Pulmonary Hypertension,  438 125. Pulmonary Nodule,  440 126. Purpura,  441 127. Red Eye,  442 128. Renal Artery Stenosis,  444 129. Renal Mass,  447 130. Renal Tubular Acidosis,  448 131. Rotator Cuff Tear,  450 132. Sarcoidosis,  451

xvii

133. Scrotal Mass,  452 134. Small-Bowel Obstruction,  453 135. Spinal Epidural Abscess,  455 136. Splenomegaly,  456 137. Stroke,  458 138. Subarachnoid Hemorrhage,  460 139. Subclavian Steal Syndrome,  461 140. Subdural Hematoma,  462 141. Superior Vena Cava Syndrome, 463 142. Syncope,  466 143. Testicular Mass,  468 144. Testicular Torsion,  469 145. Thoracic Outlet Syndrome,  471 146. Thrombocytopenia,  473 147. Thrombocytosis,  474 148. Thyroid Nodule,  475 149. Thyroiditis,  476 150. Tinnitus,  477 151. Transient Ischemic Attack (TIA), 478 152. Urethral Discharge,  479 153. Urolithiasis,  480 154. Urticaria,  482 155. Vaginal Discharge,  483 156. Vertigo,  484 157. Viral Hepatitis,  485 158. Weight Gain,  486 159. Weight Loss, Involuntary,  487 Appendix I General Guidelines for Ordering Computed Tomography, 489 Appendix II General Guidelines for Ordering Computed Tomography Angiography (CTA),  491 Appendix III General Guidelines for Ordering Magnetic Resonance Imaging (MRI),  493 Appendix IV The Electrocardiogram (ECG), 495 Appendix V Pulmonary Function Testing, 507 Index, 517

This page intentionally left blank

     

FERRI’S BEST TEST

This page intentionally left blank

     

SECTION

I

Diagnostic Imaging

1

2

Section I  n  Diagnostic Imaging Section I Diagnostic Imaging

This section deals with common diagnostic imaging tests. Each test is approached with the following format: Indications, Strengths, Weaknesses, and Comments. The comparative cost of each test is also indicated. Please note that there is considerable variation in the charges and reimbursement for each diagnostic imaging procedure, based on individual insurance and geographic region. The costs described in this book are in most cases based on the Resource-Based Relative Value Scale (RBRVS) fee schedule provided by the Centers for Medicare and Medicaid Services for total component billing. $ Relatively inexpensive–$$$$$ Very expensive . Abdominal and Gastrointestinal (GI) Imaging A 1. Abdominal film, plain (kidney, ureter, and bladder [KUB]) 2. Barium enema (BE) 3. Barium swallow (esophagram) 4. Upper GI (UGI) series 5. Computed tomographic colonography (CTC, virtual colonoscopy) 6. CT scan of abdomen and pelvis 7. CT enterography 8. CT enteroclysis 9. Magnetic resonance enterography (MRE) 10. Cholescintigraphy (hepatobiliary iminodiacetic acid [HIDA] scan, diisopropyl iminodiacetic acid [DISIDA] scan) 11. Endoscopic retrograde cholangiopancreatography (ERCP) 12. Percutaneous biliary procedures 13. Magnetic resonance cholangiopancreatography (MRCP) 14. Meckel scan (Tc-99m pertechnetate scintigraphy) 15. MRI scan of abdomen/pelvis 16. Small-bowel series 17. Tc-99m sulfur colloid (Tc-99m SC) scintigraphy for GI bleeding 18. Tc-99m-labeled red blood cell (RBC) scintigraphy for GI bleeding 19. Ultrasound of abdomen 20. Ultrasound of appendix 21. Ultrasound of gallbladder and bile ducts 22. Ultrasound of liver 23. Ultrasound of pancreas 24. Endoscopic ultrasound (EUS) 25. Video capsule endoscopy (VCE) 26. Transient elastography (FibroScan) B. Breast Imaging 1. Mammogram 2. Breast ultrasound 3. MRI of the breast C. Cardiac Imaging 1. Stress echocardiography 2. Cardiovascular radionuclide imaging (thallium, sestamibi, dipyridamole [Persantine] scan), positron emission tomography (PET), single-photon emission computed tomography (SPECT) 3. Cardiac MRI (CMR) 4. Multidetector CT scan (Non-contrast CT scan for coronary artery calcium scoring) 5. Transesophageal echocardiogram (TEE) 6. Transthoracic echocardiography (TTE) 7. Intravascular ultrasound (IVUS)

Section I  n  Diagnostic Imaging

3

D. Chest Imaging 1. Chest radiograph 2. CT scan of chest 3. MRI scan of chest E. Endocrine Imaging 1. Adrenal medullary scintigraphy (metaiodobenzylguanidine [MIBG] scan) 2. Parathyroid (PTH) scan 3. Thyroid scan (radioiodine uptake study) 4. Thyroid ultrasound F. Genitourinary Imaging 1. Obstetric ultrasound 2. Pelvic ultrasound 3. Prostate ultrasound 4. Renal ultrasound 5. Scrotal ultrasound 6. Transvaginal (endovaginal) ultrasound 7. Urinary bladder ultrasound 8. Hysterosalpingography (HSG) 9. Intravenous pyelography (IVP) and intravenous retrograde pyelography G. Musculoskeletal and Spinal Cord Imaging 1. Plain x-ray films of skeletal system 2. Bone densitometry (dual-energy x-ray absorptiometry [DEXA] scan) 3. MRI scan of spine 4. MRI scan of shoulder 5. MRI scan of hip and extremities 6. MRI scan of pelvis 7. MRI scan of knee 8. CT scan of spinal cord 9. Arthrography 10. CT myelography 11. Nuclear imaging (bone scan, gallium scan, white blood cell [WBC] scan) H. Neuroimaging of Brain 1. CT scan of brain 2. MRI scan of brain I. Positron Emission Tomography (PET) J. Single-Photon Emission Computed Tomography (SPECT) K. Vascular Imaging 1. Angiography 2. Aorta ultrasound 3. Arterial ultrasound 4. Captopril renal scan (CRS) 5. Carotid ultrasonography 6. Computed tomographic angiography (CTA) 7. Cardiac computed tomography angiography 8. Computed tomography perfusion (CTP) imaging 9. Cardiac catheterization and angiography 10. Magnetic resonance angiography (MRA) 11. Magnetic resonance direct thrombus imaging (MRDTI) 12. Pulmonary angiography 13. Transcranial Doppler 14. Venography 15. Compression ultrasonography and venous Doppler ultrasound 16. Ventilation/perfusion (V/Q) lung scan

Section I  n  Diagnostic Imaging

4

L. Oncology 1. Whole-body integrated (dual-modality) PET-CT 2. Whole-body MRI 

A.  Abdominal and Gastrointestinal (GI) Imaging 1.  Abdominal Film, Plain (Kidney, Ureter, and Bladder [KUB]) Indications • Abdominal pain • Suspected intraperitoneal free air (pneumoperitoneum) • Bowel distention 

Strengths

• Low cost • Readily available • Low radiation 

Weaknesses

• Low diagnostic yield • Contraindicated in pregnancy • Presence of barium from recent radiographs will interfere with interpretation • Nonspecific test 

Comments

• KUB is a coned plain radiograph of the abdomen that includes kidneys, ureters, and bladder. • A typical abdominal series includes flat and upright radiographs. • KUB is valuable as a preliminary study when investigating abdominal pain and pathologic findings (e.g., pneumoperitoneum, bowel obstruction [Fig. 1.1], calcifications). Fig. 1.2 describes normal gas pattern. Normal gas collections under the diaphragm can also be seen on chest radiographs (Fig. 1.3).

*

A

B

Fig. 1.1  Supine (A) and erect (B) abdominal plain films in two patients with adhesive small-bowel obstruction. (A) Air-filled distended small-bowel loops (arrows) with collapsed colon (asterisk). Note that the small-bowel folds (valvulae conniventes) typically extend completely across the intestinal loops. (B) Multiple air-fluid levels in dilated small-bowel loops (arrows) in the context of nondistended colon. (From Feldman M, Friedman LS, Brandt LJ: Sleisenger and Fordtran’s gastrointestinal and liver disease, ed 10, Philadelphia, 2016, Elsevier.)

Section I  n  Diagnostic Imaging

5

st hf

tc sf

cec

sb

ESOPHAGUS

GASTRIC RUGAE GASTRIC CANAL PYLORUS PYLORIC SPHINCTER

sig

A

B

SEMILUNAR FOLDS

CIRCULAR FOLDS

C

DUODENUM

SMALL INTESTINE LARGE INTESTINE

Fig. 1.2  (A–C) Normal bowel gas pattern. Gas is normally swallowed and can be seen in the stomach (st). Small amounts of air normally can be seen in the small bowel (sb), usually in the left mid-abdomen or the central portion of the abdomen. In this patient, gas can be seen throughout the entire colon, including the cecum (cec). In the area where the air is mixed with feces, there is a mottled pattern. Cloverleaf-shaped collections of air are seen in the hepatic flexure (hf), transverse colon (tc), splenic flexure (sf), and sigmoid (sig). (From Mettler FA: Primary care radiology, Philadelphia, 2000, Saunders.)

• This is the least expensive but also least sensitive method to assess bowel obstruction radiographically. • Cost: $ 

2.  Barium Enema (BE) Indications

• Colorectal carcinoma • Diverticular disease (Fig. 1.4) • Inflammatory bowel disease (IBD) • Lower GI bleeding • Polyposis syndromes • Constipation • Evaluation for leak of postsurgical anastomotic site 

Strengths

• Readily available • Relatively inexpensive • Good visualization of mucosal detail with double-contrast barium enema (DCBE) 

Weaknesses

• Uncomfortable bowel preparation and procedure for most patients • Risk of bowel perforation (incidence 1:5000)

6

Section I  n  Diagnostic Imaging

R

L

Fig. 1.3  Colonic interposition. This is a normal variant in which the hepatic flexure can be seen above the liver. This is seen as a gas collection under the right hemidiaphragm (arrow), but it is clearly identified as colon, owing to the transverse haustral markings. (From Mettler FA: Essentials of radiology, ed 3, Philadelphia, 2014, Elsevier.)

Fig. 1.4  Diverticular disease showing typical muscle changes in the sigmoid and diverticula arising from the apices of the clefts between interdigitating muscle folds. (From Grainger RG, Allison D: Grainger and Allison’s diagnostic radiology: a textbook of medical imaging, ed 4, Sydney, 2001, Churchill Livingstone.)

Section I  n  Diagnostic Imaging

7

• Contraindicated in pregnancy • Can result in severe postprocedure constipation in older adult patients • Poorly cleansed bowel will interfere with interpretation • Poor visualization of rectosigmoid lesions 

Comments

• BE is now rarely performed or indicated. Colonoscopy is more sensitive and specific for evaluation of suspected colorectal lesions. • This test should not be performed in patients with suspected free perforation, fulminant colitis, severe pseudomembranous colitis, or toxic megacolon, or in a setting of acute diverticulitis. • A single-contrast BE uses thin barium to fill the colon, whereas DCBE uses thick barium to coat the colon and air to distend the lumen. Single-contrast BE is generally used to rule out diverticulosis, whereas DCBE is preferable for evaluating colonic mucosa, detecting small lesions, and diagnosing IBD. • Cost: $$ 

3.  Barium Swallow (Esophagram) Indications

• Achalasia • Esophageal neoplasm (primary or metastatic) (Fig. 1.5) • Esophageal diverticula (e.g., Zenker diverticulum), pseudodiverticula • Suspected aspiration, evaluation for aspiration after stroke • Suspected anastomotic leak • Esophageal stenosis or obstruction • Extrinsic esophageal compression • Dysphagia

Fig. 1.5  “Bird’s beak” appearance of lower esophagus during an upper gastrointestinal radiographic swallow study. (From Cameron JL, Cameron AC, editors: Current surgical therapy, ed 10, St. Louis, 2011, Saunders;1269–1273.)

8

Section I  n  Diagnostic Imaging

• Esophageal tear or perforation • Fistula (aortoesophageal, tracheoesophageal) • Esophagitis (infectious, chemical) • Mucosal ring (e.g., Schatzki ring) • Esophageal webs (e.g., Plummer-Vinson syndrome) 

Strengths

• Low cost • Readily available 

Weaknesses

• Contraindicated in pregnancy • Requires patient cooperation • Radiation exposure 

Comments

• In a barium swallow study, the radiologist observes the swallowing mechanism while films of the cervical and thoracic esophagus are obtained. • Barium is generally used because it provides better anatomic detail than water-soluble contrast agents; however, diatrizoate (Hypaque) or Gastrografin should be used rather than barium sulfate in suspected perforation or anastomotic leak because free barium in the peritoneal cavity induces a granulomatous response that can result in adhesions and peritonitis; in the mediastinum, free barium can result in mediastinitis. • Cost: $ 

4.  Upper GI (UGI) Series Indications

• Gastroesophageal reflux disease (GERD) • Peptic ulcer disease • Esophageal carcinoma • Gastric carcinoma (Fig. 1.6) • Gastric lymphoma • Gastric polyps • Gastritis (hypertrophic, erosive, infectious, granulomatous) • Gastric outlet obstruction • Gastroparesis • Metastatic neoplasm (from colon, liver, pancreas, melanoma)

Fig. 1.6  Gastric adenocarcinoma of the stomach (arrows). (From Talley NJ, Martin CJ: Clinical gastroenterology, ed 2, Sydney, 2006, Churchill Livingstone.)

Section I  n  Diagnostic Imaging

9

• Congenital abnormalities (e.g., hypertrophic pyloric stenosis, antral mucosal diaphragm) • Evaluation for complications after gastric surgery 

Strengths

• Inexpensive • Readily available 

Weaknesses

• Contraindicated in pregnancy • Can result in significant postprocedure constipation in older adult patients • Requires patient cooperation • Radiation exposure 

Comments

• Upper endoscopy is invasive and more expensive but is more sensitive and has replaced UGI series for evaluation of esophageal and gastric lesions. • In a barium swallow examination, only films of the cervical and thoracic esophagus are obtained, whereas in a UGI series films are taken of the thoracic esophagus, stomach, and duodenal bulb. • Barium provides better anatomic detail than water-soluble contrast agents; however, water-soluble contrast agents (Gastrografin, Hypaque) are preferred when perforation is suspected or postoperatively to assess anastomosis for leaks or obstruction, because free barium in the peritoneal cavity can produce a granulomatous response that can result in adhesions. • It is necessary to clean out the stomach with nasogastric (NG) suction before performing contrast examination when gastric outlet obstruction is suspected. • Cost: $$ 

5. Computed Tomographic Colonography (CTC, Virtual Colonoscopy) Indication • Screening for colorectal carcinoma 

Strengths

• May be more acceptable to patients than fiberoptic colonoscopy • Does not require sedation • Safer than fiberoptic colonoscopy • Lower cost than fiberoptic colonoscopy • Standard examination does not require intravenous (IV) contrast • Also visualizes abdomen and lower thorax and can detect abnormalities there (e.g., aortic aneurysms, cancers of ovary, pancreas, lung, liver, kidney) 

Weaknesses

• Failure to detect clinically important flat lesions, which do not protrude into the lumen of the colon • Need for cathartic preparation; requires the same bowel preparation as colonoscopy • Lack of therapeutic ability; nearly 10% of patients require follow-up traditional colonoscopies because of abnormalities detected by CTC • Incidental findings detected on CTC can lead to additional and often unnecessary testing • Radiation exposure 

Comments

• CTC uses a computed tomography (CT) scanner to take a series of radiographs of the colon and a computer to create a three-dimensional (3-D) view (Fig. 1.7). It can be uncomfortable because the patient is not sedated and a small tube is inserted in the rectum to inflate the colon so that it can be more easily viewed.

10

Section I  n  Diagnostic Imaging

(Ai)

(Aii)

(Aiii)

(B)

Fig. 1.7  Colon polyps seen at (Ai–Aiii) colonoscopy and (B) computed tomography colonography. (Aii) is after endoscopic resection of the polyps in (Ai). (From Ballinger A: Kumar and Clark’s essentials of clinical medicine, ed 5, Edinburgh, 2012, Saunders.) • CTC uses a low-dose x-ray technique, typically 20% of the radiation used with standard diagnostic CT, and approximately 10% less than double-contrast barium enema (DCBE). • Most insurance companies do not pay for CTC, but that could change if colon cancer screening guidelines endorse it. • Sensitivity ranges from 85% to 94%, and specificity is approximately 96% for detecting large (≥1 cm) polyps. • Cost: $$$ 

6.  CT Scan of Abdomen and Pelvis Indications

• Evaluation of abdominal mass, pelvic mass • Suspected lymphoma • Evaluation and staging of neoplasm of abdominal and pelvic organs (Fig. 1.8) • Splenomegaly • Intraabdominal, pelvic, or retroperitoneal abscess • Abdominal and pelvic trauma • Jaundice • Pancreatitis: contrast-enhanced CT is considered the gold standard for diagnosing pancreatic necrosis and peripancreatic collections, and for grading acute pancreatitis

Section I  n  Diagnostic Imaging Noncontrast

Arterial

Portal venous

Delayed

11

Fig. 1.8  Dynamic CT of a patient with HCC showing no lesion in the noncontrast phase, an enhancing lesion in the right lobe of the liver in the arterial phase of contrast administration (arrow), and a faint lesion in the portal venous phase, seen better in the delayed phase. (From Feldman M, Friedman LS, Brandt LJ: Sleisenger and Fortran’s gastrointestinal and liver disease, ed 10, Philadelphia, 2016, Elsevier.) • Suspected bowel obstruction • Appendicitis • IBD 

Strengths

• Fast • Noninvasive 

Weaknesses

• Potential for significant contrast reaction • Suboptimal sensitivity for traumatic injury of the pancreas, diaphragm, small bowel, and mesentery • Retained barium from other recent studies will interfere with interpretation • Expensive • Contraindicated in pregnancy • Radiation exposure 

Comments

• CT with contrast is the initial diagnostic imaging of choice in patients with left lower quadrant (LLQ) and right lower quadrant (RLQ) abdominal pain or mass in adults. Ultrasound is preferred as the initial imaging modality in children, young women, and in the evaluation of right upper quadrant (RUQ) and mid-abdominal pain or mass unless the patient is significantly obese (poor visualization).

12

Section I  n  Diagnostic Imaging

• CT of abdomen and pelvis with contrast is the imaging procedure of choice for suspected abdominal or pelvic abscess in adults. • CT is 90% sensitive for small-bowel obstruction. • The orientation of CT and magnetic resonance imaging (MRI) scans is described in Fig. 1.9. Fig. 1.10 illustrates the structures seen on a normal CT of the abdomen and pelvis. Fig. 1.11 illustrates the normal pancreas with IV and oral contrast. • Cost: CT without contrast $$, CT with contrast $$$, CT with and without contrast $$$

 7.  CT Enterography Indications

• CT enterography using multidetector CT (MDCT), which improves image quality by limiting motion artifacts, is a first-line modality for examination of small-bowel disease. • Indications for CT enterography include Crohn disease and other suspected inflammatory bowel diseases, intermittent small-bowel obstruction, obscure GI bleeding, and suspected tumors of the small bowel.

 Strengths

• Fast • Noninvasive • Advantages of CT enterography over traditional barium-based small-bowel followthrough examination include demonstration of the entire thickness of the bowel wall and disease in the mesentery, as well as display of bowel loops without superimposition.

Fig. 1.9  Orientation of computed tomography (CT) and magnetic resonance (MR) images. CT and MR usually present images as transverse (axial) slices of the body. The orientation of most slices is the same as that of a patient viewed from the foot of the bed. (From Mettler FA: Primary care radiology, Philadelphia, 2000, Saunders.)

Section I  n  Diagnostic Imaging

Left lobe of liver

13

Splenic flexure of colon

Right lobe of liver Inferior vena cava

Fundus of stomach Aorta

Lower lobe of right lung

Spleen

A

Body of stomach with gas Colon

Lateral segment of left lobe Medial segment of left lobe

Tail of pancreas

Right lobe of liver

Splenic vessels

Right adrenal gland Crus of diaphragm

Lower lobe of left lung

Spleen

B

Left kidney

Gas in stomach Falciform ligament Porta hepatis

Body of pancreas

Portal vein

Descending colon

Inferior vena cava

Splenic vein

Aorta

Left adrenal gland Spleen

C

Left kidney

Gallbladder Superior mesenteric vein

Transverse colon Superior mesenteric artery

Head of pancreas

Jejunum

Duodenum

Left renal vein

Inferior vena cava Right kidney

Left kidney

D

Fig. 1.10  Normal transverse computed tomography anatomy of the abdomen and pelvis. The patient has been given oral, rectal, and intravenous contrast media. (From Mettler FA: Essentials of radiology, ed 3, Philadelphia, 2014, Elsevier.) Continued

14

Section I  n  Diagnostic Imaging

Superior mesenteric artery and vein

Transverse colon Hepatic flexure of colon

Jejunum

Right lobe of liver

Aorta

Third portion of duodenum Inferior vena cava Right ureter

Left ureter Descending colon

E

Ileum

Iliac veins

Right ureter

Left ureter Bifurcation of aorta

Iliac crest

Left psoas

F Sigmoid colon Rectus abdominis

lliopsoas muscle Rectosigmoid

External iliac artery and vein lleum

Left ureter

Right ureter Internal iliac artery and vein

Sacrum

G

External iliac artery External iliac vein

Bladder

Right acetabulum

Vesical venous plexus

Right ureter entering bladder Seminal vesicles

Rectum Sacrum

H Fig. 1.10 cont’d

Section I  n  Diagnostic Imaging

15

Femoral artery Femoral vein

Symphysis pubis

Right femoral head

Prostate

Greater trochanter of femur Rectum

Coccyx

I

Sigmoid

Broad ligament Left ureter

Right ureter Uterus

Rectum

J

Small bowel Contrast in bladder Tampon

Cervix Gas in rectum

Contrast in rectum

K

Symphysis pubis Vagina

Tampon Rectal tube

L Fig. 1.10 cont’d

16

Section I  n  Diagnostic Imaging common bile duct surrounded by pancreatic head

duodenum

body of pancreas

peripancreatic fat is nearly black, indicating no inflammatory stranding tail of pancreas spleen

inferior vena cava

portal vein

aorta

Fig. 1.11  Normal pancreas, computed tomography with intravenous (IV) and oral contrast, soft-tissue window. This scan shows a normal pancreas. In many patients, the pancreas is not so horizontally oriented and is therefore difficult to see in a single slice. Here the common course of the pancreas is seen. The pancreatic head is draped over the portal vein. The tail of the pancreas crosses the midline and then moves posteriorly. It crosses the left kidney and ends medial to the spleen. The duodenum is to the right of the pancreatic head, filled with oral contrast. The common bile duct is seen as a hypodense area within the pancreatic head because it is filled with bile. The contrast between the dark bile and the bright pancreatic tissue is increased by the administration of IV contrast, because the pancreas enhances as a result of high blood flow. The fat surrounding the pancreas is dark, which is normal and indicates the absence of inflammatory stranding; almost the entire pancreas is outlined in fat and has a distinct border. Incidentally, the patient has an abnormal dilated gallbladder with pericholecystic fluid. Given this finding, the prominent common bile duct should be inspected further for an obstructing stone. (From Broder JS: Diagnostic imaging for the emergency physician, Philadelphia, 2011, Saunders.)

 Weaknesses

• Requires fasting for 4 to 6 hours before procedure • Potential for significant contrast reaction • Retained barium from other recent studies will interfere with interpretation • Relatively contraindicated in pregnancy • Radiation exposure 

Comments

• CT enterography differs from routine CT of the abdomen and pelvis in the use of large volumes of low-attenuation intraluminal contrast agent to optimally distend the bowel lumen, matched with thin-slice collimation and routine high-detail coronal and sagittal reformations. Low-attenuation intraluminal contrast paired with intravenous contrast administration optimally displays both the lumen and wall of the small bowel (Fig. 1.12).

Section I  n  Diagnostic Imaging

17

S

B

Fig. 1.12  Computed tomography (CT) enterography. Coronal image from a CT enterography examination using low-attenuation intraluminal contrast and intravenous contrast shows the normal fold pattern of the jejunum (arrowhead) and the normal absence of folds of the ileum (arrow). The stomach (S) is well distended with intraluminal contrast agent. The bladder (B) is also filled. (From Webb WR, Brant WE, Major NM: Fundamentals of body CT, ed 4, Philadelphia, 2015, Saunders.)

 8.  CT Enteroclysis Indication

• Performed on patients with small-bowel obstruction to find the level and cause of obstruction (Fig. 1.13) 

Weaknesses

• Potential for significant contrast reaction • Contraindicated in pregnancy • Radiation exposure 

Comments

• For CT enteroclysis, contrast medium for small-bowel distention is injected into the small bowel through a nasojejunal tube rather than given orally as for CT enterography. A nasojejunal tube is positioned at the duodenojejunal junction under fluoroscopic guidance. A total volume of 1200 to 1600 mL of low-attenuation oral contrast medium is injected into the small bowel at 60 to 120 mL/

18

Section I  n  Diagnostic Imaging

Fig. 1.13  Computed tomography (CT) enteroclysis: distal small-bowel obstruction. Coronal image from a CT enteroclysis examination shows diffuse dilatation of the small bowel with low-attenuation intraluminal contrast agent and air. An adhesion was the cause of this obstruction. (From Webb WR, Brant WE, Major NM: Fundamentals of body CT, ed 4, Philadelphia, 2015, Saunders.) min. Glucagon or other antispasmodic medication is administered. Intravenous contrast is used, and MDCT scanning is performed using the same parameters as for CT enterography.

 9.  Magnetic Resonance Enterography (MRE) Indication

• Evaluation of small and large bowel in patients with IBD (Fig. 1.14) 

Strengths

• Depicts extraluminal abnormalities • Useful to distinguish active from fibrotic strictures. Findings of intestinal wall thickening, submucosal edema, vasa recta engorgement, and lymphadenopathy are signs of active disease (Fig. 1.15) • Better delineation of fistulas • Not affected by overlying gas (unlike ultrasound) • No ionizing radiation 

Weaknesses

• Relatively long acquisition times • Expensive • May miss early mucosal lesions

Section I  n  Diagnostic Imaging

A

19

B

Fig. 1.14  Axial (A) and coronal (B) T2-weighted images from a magnetic resonance enterography showing thickening of the terminal ileum (arrow) with fat stranding (double arrow) in the surrounding mesentery in a patient with known Crohn disease. (From Fielding JR, et al: Gynecologic imaging, Philadelphia, 2011, Saunders.)

Fig. 1.15  MR enterography with gadolinium contrast in a patient with Crohn disease. This coronal view shows mural hyperenhancement, mural thickening, and the comb sign (engorged perienteric vasculature) involving the terminal ileum. The vessels are seen medial to the inflamed loop and resemble the teeth of a comb. (Courtesy Dr. Edward Loftus and Dr. Jeffrey Fidler, Rochester, Minn.)

 Comments

• Requires fasting for 6 hours before procedure. • Using dynamic fast imaging employing steady-state acquisition (FIESTA) images can add information regarding the functional status of fibrotic segments. Using these criteria, compared with the gold standard of ileocolonoscopy with biopsies, MRI images can yield a diagnostic accuracy of 90%. • Cost: $$$ 

20

Section I  n  Diagnostic Imaging

10.  Cholescintigraphy (Hepatobiliary Iminodiacetic Acid [HIDA] Scan, Diisopropyl Iminodiacetic Acid [DISIDA] Scan) Indications

• Acute cholecystitis (normal ultrasound but high clinical suspicion for acalculous cholecystitis) • Chronic acalculous cholecystitis • Bile leak • Postcholecystectomy syndrome • Obstruction of bile flow (normal ultrasound but high suspicion for cystic duct calculus) • Biliary dyskinesia • Biliary atresia • Afferent loop syndrome • Evaluation of focal liver lesions 

Strengths

• Not operator dependent • Can be performed on an emergency basis in a nonfasting patient • High specificity for excluding acute cholecystitis • Use of HIDA may be limited in jaundiced patients, but DISIDA may allow imaging of the biliary tree in patients with serum bilirubin values as high as 20 mg/dL 

Weaknesses

• Severe hepatocellular dysfunction with bilirubin greater than 20 mg/dL will result in poor excretion and nondiagnostic study • Recent or concomitant use of opiates or meperidine may interfere with bile flow • False positives common • Time-consuming (requires more than 1 hour of actual imaging time and patient preparation)

 Comments

• In a normal scan, the radiopharmaceutical is cleared from the blood pool after 5 minutes, there is noticeable liver clearing after 30 minutes, and gallbladder and bowel activity is visualized after 60 minutes. Images are obtained every 5 minutes for 1 hour. Late images can be obtained for up to 4 hours after injection. Nonvisualization of the gallbladder is indicative of cholecystitis (Fig. 1.16).

Fig. 1.16  Acute cholecystitis, hot rim sign (arrows), is suspicious for gangrenous gallbladder. Curvilinear area of relatively increased activity in liver adjacent to gallbladder (GB) persists in delayed images. Anterior, right anterior oblique, and right lateral views start at 40 minutes after injection. GB did not visualize at 4 hours (not shown). (From Specht N: Practical guide to diagnostic imaging, St. Louis, 1998, Mosby.)

Section I  n  Diagnostic Imaging

21

• This test is most helpful when clinical suspicion for cholecystitis is high and ultrasound results are inconclusive. A positive scan result is defined as nonvisualization of the gallbladder with preserved excretion into the bile duct or small intestine. The accuracy of the test for detecting acute cholecystitis is 92%, superior to that of ultrasound. • Food intake will interfere with test. Optimal fasting is 4 to 12 hours. Fasting longer than 24 hours will also lead to inconclusive examination. • Cost: $$$ 

11.  Endoscopic Retrograde Cholangiopancreatography (ERCP) Indications

• Evaluation and treatment of diseases of the bile ducts and pancreas • Treatment of choice for bile duct stones (Fig. 1.17) and for immediate relief of extrahepatic biliary obstruction in benign disease • Other indications are biliary obstruction caused by cancer, acute and recurrent pancreatitis, pancreatic pseudocyst, suspected sphincter of Oddi dysfunction • Can be used for diagnostic purposes when magnetic resonance cholangiography (MRCP) and other imaging studies are inconclusive or unreliable, such as in suspected cases of primary sclerosing cholangitis early in the disease, when the changes in duct morphologic characteristics are subtle, or in patients with nondilated bile duct and clinical signs and symptoms highly suggestive of gallstone or biliary sludge • Preferred modality in patients with high pretest probability of sphincter dysfunction or ampullary stenosis 

Strengths

• Preferred modality for treatment of common bile duct stones (Fig. 1.18) • Well suited to evaluate for and treat bile duct leaks and biliary tract injury after open or laparoscopic biliary surgery • ERCP in management of pancreatic and biliary cancer allows access to obstructed bile and pancreatic ducts for collecting tissue samples and placing stents to temporarily relieve obstruction

Fig. 1.17 Endoscopic retrograde cholangiopancreatography. The fiberoptic scope is passed into the duodenum. Note the small catheter being advanced into the biliary duct. (From Pagana KD, Pagana TJ: Mosby’s diagnostic and laboratory test reference, ed 8, St. Louis, 2007, Mosby.)

22

Section I  n  Diagnostic Imaging

Fig. 1.18 Endoscopic retrograde cholangiopancreatography demonstrating gallstones within the gallbladder and common bile duct. (From Talley NJ, Martin CJ: Clinical gastroenterology, ed 2, Sydney, 2006, Churchill Livingstone.)

 Weaknesses

• Invasive, technically difficult procedure • Five percent to 7% risk of pancreatitis depending on patient, procedure, and operator expertise; other complications, such as bleeding, cholangitis, cholecystitis, cardiopulmonary events, perforation, and death, occur far less often 

Comments

• In ERCP, contrast-agent injection is performed through the endoscope after cannulation of the common bile duct (CBD). Complications include pancreatitis, duodenal perforation, and GI bleeding. • Although the complication rate of ERCP is acceptable compared with other invasive procedures such as biliary bypass surgery or open bile duct exploration, the rate is too high for patients with a low pretest probability of disease if the procedure is to be done purely diagnostically. • Centers that perform a significant volume of ERCP have higher completion rates and lower complication rates. • ERCP is not indicated for the management of mild pancreatitis or nonbiliary pancreatitis, and its overall use in patients with acute pancreatitis continues to be debated. • Cost: $$$$ 

12.  Percutaneous Biliary Procedures Indications

• Transhepatic cholangiogram (Fig. 1.19): used for demonstration of biliary anatomy, first step before biliary drainage or stent placement, diagnosis of primary sclerosing cholangitis (Fig. 1.20) • Biliary drainage: used for biliary obstruction • Biliary stent placement: used for malignant biliary stricture (Fig. 1.21), inability to place endoscopic stent 

Weaknesses

• Invasive • Operator dependent • Cost: $$$$

Section I  n  Diagnostic Imaging

A

B

C

D

23

Fig. 1.19  Schematic showing percutaneous transhepatic cholangiography. (A) A peripheral bile duct is identified and entered with a needle. (B) A guidewire is passed through the needle across the obstructing lesion into the duodenum. (C) The needle has been withdrawn. (D) An internal-external catheter is inserted over the guidewire. (From Feldman M, Friedman LS, Brandt LJ: Sleisenger and Fordtran’s gastrointestinal and liver disease, ed 10, Philadelphia, 2016, Elsevier.)

 13.  Magnetic Resonance Cholangiopancreatography (MRCP) Indications

• Suspected biliary or pancreatic disease • Unsuccessful ERCP, contraindication to ERCP, and presence of biliary enteric anastomoses (e.g., choledochojejunostomy, Billroth II anastomosis) 

Strengths

• Advantages over ERCP: noninvasive, less expensive, requires no radiation, less operator dependent, allows better visualization of ducts proximal to obstruction, and can allow detection of extraductal disease when combined with conventional T1W and T2W sequences • Useful in patients who have biliary or pancreatic pain but no objective abnormalities in liver tests or routine imaging studies • Can detect retained stone with sensitivity of 92% and specificity of 97% (Fig. 1.22) 

Weaknesses

• Limitations of MRCP include artifacts caused by surgical clips, pneumobilia, or duodenal diverticula; and for use in patients with implantable devices or claustrophobia • Accuracy diminished by stones 1 mm or less and normal bile duct diameter (0.1 mL/min) at time of injection • Window for detection of bleeding after injection is approximately 1 hour • Not useful for intermittent bleeding • Inexact localization of bleeding site; because blood acts as an intestinal irritant, movement can often be rapid and bidirectional, making it difficult to localize site of bleeding

30

Section I  n  Diagnostic Imaging

• Liver and spleen uptake may obscure splenic or hepatic flexure source • Ectopic spleen and asymmetric bone marrow activity can interfere with detection of bleeding • Presence of barium in GI tract may obscure bleeding site 

Comments

• After injection of Tc-99m SC, radiotracer will extravasate at the bleeding site into the lumen with each recirculation of blood. The site of bleeding is seen as a focal area of radiotracer accumulation that increases in intensity and moves through the GI tract. • Tc-99m SC is less sensitive than Tc-99m red blood cell (RBC) scan and is used less often for evaluation of GI hemorrhage. • Cost: $$ 

18.  Tc-99m-Labeled Red Blood Cell (RBC) Scintigraphy for GI Bleeding Indication • Localization of GI bleeding of undetermined source 

Strengths

• Major advantage over Tc-99m SC is that a hemorrhagic site can be detected over a much longer period and can reimage if bleeding not seen immediately and patient rebleeds • In addition to detecting active bleeding sites, may be able to detect vascular blushes of tumors, angiodysplasia, and AV malformations 

Weaknesses

• False-positive results caused by misinterpretation of normal variants or poorly detailed delayed images • Time-consuming; not indicated in patient actively bleeding and clinically unstable • Inexact localization of bleeding site; because blood acts as an intestinal irritant, movement can often be rapid and bidirectional, making it difficult to localize site of bleeding • Presence of barium in GI tract may obscure bleeding site • Visualization requires a bleeding rate greater than 0.1 mL/min 

Comments

• In an RBC scan, the patient’s RBCs are collected, labeled with a radioisotope, and then returned to the patient’s circulation. • Criteria for positive Tc-RBC scintigraphy are as follows: abnormal radiotracer “hot” spot appears and conforms to bowel anatomy, normal activity persists or increases over time (Fig. 1.26), and there is noticeable movement of activity by peristalsis, retrograde, or anterograde. • Cost: $$ 

19.  Ultrasound of Abdomen Indications

• Abdominal pain • Jaundice • Cholelithiasis (Fig. 1.27) • Cholecystitis • Elevated liver enzymes • Splenomegaly • Ascites • Abdominal mass • Pancreatitis • Portal vein thrombosis (Fig. 1.28)

Section I  n  Diagnostic Imaging liver

31

liver

B

A iliac artery

radiotracer bladder accumulation in right lower quadrant

liver

C iliac artery radiotracer accumulation in right lower quadrant indicating gastrointestinal hemorrhage

Fig. 1.26 Gastrointestinal hemorrhage, tagged red blood cell study. This 58-year-old presented with bright red blood per rectum. A Tc-99m tagged red blood cell study was performed. (A) Acquired 10 minutes after injection of the labeled red cells. (B) Acquired 45 minutes after injection. (C) Acquired 55 minutes after injection. A focus of radiotracer activity is seen gradually accumulating in the right lower quadrant, consistent with hemorrhage within the cecum. Normal tracer is also seen in the region of the liver (because this is a vascular organ), in the iliac arteries, and in the urinary bladder. (From Broder JS: Diagnostic imaging for the emergency physician, Philadelphia, 2011, Saunders.) GALLBLADDER

AS

Fig. 1.27  Acoustic shadowing from gallstones. AS, Acoustic shadow. (From Cameron P, Little M, Mitra B, et al: Textbook of adult emergency medicine, ed 5, Sydney, 2020, Elsevier.)

 Strengths

• Fast • Can be performed at bedside • No ionizing radiation • Widely available • Can provide Doppler and color flow information • Lower cost than CT

32

Section I  n  Diagnostic Imaging

H.ARTERY

PORTAL VN

THROMBUS

Fig. 1.28  Portal venous thrombosis. Partial portal venous thrombosis is visible on B mode as echoreflective material on one side of the vein (arrows). Doppler examination is always required to assess patency, as some thrombi are of reduced echoreflectivity and may not be visible on B mode. (From Grainger RG, Allison DJ, Adam A, Dixon AK, editors: Grainger and Allison’s diagnostic radiology, ed 4, Philadelphia, 2001, Churchill Livingstone.)

 Weaknesses

• Obscuring intestinal gas • Only able to visualize 50% of bile duct stones • Inferior anatomic detail compared with CT • Affected by body habitus • Cannot be used to definitely rule out abscess 

Comments

• This is often the initial diagnostic procedure of choice in patients presenting with abdominal pain or mass in RUQ and mid-abdomen. CT of abdomen is preferred in LLQ and RLQ pain or mass and in significantly obese patients. • The presence of a sonographic Murphy sign (the ultrasonographer elicits focal gallbladder tenderness under the ultrasound transducer) has a positive predictive value greater than 90% for acute cholecystitis if gallstones are present. • Ultrasound should be considered as an initial test in all patients with pancreatitis, especially if gallstones are suspected. • Cost: $$ 

20.  Ultrasound of Appendix Indication

• Suspected appendicitis (Fig. 1.29) 

Strengths

• Fast • Readily available • Noninvasive • No ionizing radiation 

Weaknesses

• Can be affected by overlying bowel gas and body habitus (e.g., obese patient) • Operator dependent; results may be affected by skill of technician 

Comments

• This is the best initial study in suspected appendicitis in children and pregnant patients. • Cost: $$

Section I  n  Diagnostic Imaging

33

B

A

C Fig. 1.29  Transabdominal ultrasonography in a 37-year-old woman with pelvic pain. (A) Cross-sectional view of a dilated appendix (large arrow) with periappendiceal fluid (small arrow). (B) Compression yields minimal change in appendiceal diameter and causes significant pain. (C) A longitudinal view of the appendix (small arrows) and its origin at the cecum (large arrows). (From Adams JG et al: Emergency medicine, clinical essentials, ed 2, Philadelphia, 2013, Elsevier.)

 21.  Ultrasound of Gallbladder and Bile Ducts Indications

• Suspected cholelithiasis: Fig. 1.30 shows a normal gallbladder ultrasound in comparison with cholelithiasis seen on ultrasound (Fig. 1.31) • Cholecystitis • Gallbladder polyps • Gallbladder neoplasms • Choledocholithiasis • Biliary neoplasm • Cholangitis • Suspected congenital biliary abnormalities (e.g., biliary atresia, Caroli disease, choledochal cyst) • Biliary dyskinesia 

Strengths

• Fast • Readily available • Can be performed at bedside • Noninvasive • No ionizing radiation 

Weaknesses

• Is affected by overlying bowel gas and body habitus (e.g., obese patient) • Operator dependent; results may be affected by skill of technician

34

Section I  n  Diagnostic Imaging

Liver GB

B Head

Ant

Feet

GB CBD

A

C

IVC

Fig. 1.30  Single gallstone. (A) On the kidney, ureter, and bladder (plain radiograph of the abdomen), a single calcification is seen in the right upper quadrant (arrow). It is not possible to tell from this one picture whether this is a gallstone, kidney stone, or calcification in some other structure. (B) A longitudinal ultrasound image in this patient clearly shows the liver, gallbladder (GB), and an echogenic focus (arrow) within the gallbladder lumen, representing the single gallstone. Also note the dark shadow behind the gallstone. (C) Another longitudinal ultrasound image, slightly more medial, also shows the inferior vena cava (IVC) and the common bile duct (CBD), which can be measured. Here it is of normal diameter. (From Mettler FA: Essentials of radiology, ed 3, Philadelphia, 2014, Elsevier.)

Fig. 1.31  Gallbladder with gallstones (Stones), thickened gallbladder wall (GBW), and pericholecystic fluid (FF). Together these findings constitute the sonographic signs of cholecystitis. (From Marx JA, et al: Rosen’s emergency medicine, ed 7, Philadelphia, 2010, Elsevier.)

• Stones smaller than 2 mm may be missed or confused with biliary sludge (layering echogenic material that does not cast shadows) 

Comments

• This is the initial best test for suspected cholelithiasis and cholecystitis. Sensitivity for detection of gallstone in the gallbladder is better than 95% for stones

Section I  n  Diagnostic Imaging

35

larger than 2 mm. Specificity is greater than 95% when stones produce acoustic shadowing. • Patient must take nothing by mouth for 4 hours but should not fast longer than 24 hours (gallbladder may be contracted). • Cost: $$ 

22.  Ultrasound of Liver Indications

• Elevated liver enzymes • Hepatomegaly • Liver mass (neoplasm, cystic disease, abscess) • Jaundice • Hepatic trauma • Hepatic parenchymal disease (e.g., fatty infiltration, hemochromatosis, hepatitis, cirrhosis, portal hypertension) • Ascites 

Strengths

• Fast. Requires only an overnight or 8-hour fasting • Widely available • Portable (can be performed at bedside) • Noninvasive • No ionizing radiation • Low cost 

Weaknesses

• Can be affected by overlying bowel gas and body habitus • Cannot be used to definitely rule out abscess • Rib artifact may obscure images of the right lobe • Rarely provides definitive diagnosis and usually requires confirmatory CT (Fig. 1.32) or MRI 

Comments

• Because of its widespread availability, noninvasive nature, and low cost, ultrasound is often performed as initial study in evaluation of suspected liver disease. • Table 1.1 compares various imaging modalities of the biliary tract • Cost: $$ 

23.  Ultrasound of Pancreas Indications • Pancreatitis • Cystic fibrosis • Pancreatic abscess • Pancreatic pseudocyst • Suspected neoplasm • Trauma 

Strengths

• Fast • Noninvasive • Can be performed at bedside • No ionizing radiation 

Weaknesses

• Is affected by overlying bowel gas and body habitus (e.g., in obese patient, fat overlying the pancreas impedes visualization). CT is preferred when suspecting pancreatitis, pancreatic neoplasm, or abscess

36

Section I  n  Diagnostic Imaging

a

SB

a

SB a SB

A R

L

SB

SB

A

A A A

A A

B Fig. 1.32  Ascites. On a plain film of the abdomen (A), only gross amount of ascites (a) can be identified. This is usually seen, because the ascites have caused a rather gray appearance of the abdomen and pushed the gas-containing loops of small bowel (SB) toward the most nondependent and central portion of the abdomen. A transverse computed tomography scan (B) shows a cross-sectional view of the same appearance with the air- and contrastfilled small bowel floating in the ascitic fluid (A). (From Mettler FA, Guiberteau MJ, Voss CM, Urbina C: Primary care radiology, Philadelphia, 2000, Elsevier.)

• Operator dependent; results may be affected by skill of technician • Barium from recent radiographs will interfere with visualization • Cannot be used to conclusively rule out abscess • Difficult to evaluate tail of pancreas because of location 

Comments • Cost: $$

Section I  n  Diagnostic Imaging

37

Table 1.1    Imaging Studies of the Biliary Tract TECHNIQUE

CONDITION TESTED FOR

US

Cholelithiasis

FINDINGS/COMMENTS Stones manifest as mobile, dependent echogenic foci within the gallbladder lumen with acoustic shadowing Sludge appears as layering echogenic material without shadows Sensitivity >95% for stones >2 mm Specificity >95% for stones with acoustic shadows Rarely, a stone-filled gallbladder may be contracted and difficult to see, with a “wall-echo-shadow” sign Best single test for stones in the gallbladder

Choledocholithiasis

Stones are seen in the BD in only ≈50% of cases but can be inferred from the finding of a dilated BD (>6-mm diameter), with or without gallstones, in another ≈25% of cases Can confirm, but not exclude, BD stones

Acute cholecystitis

Sonographic Murphy sign (focal gallbladder tenderness under the transducer) has a positive predictive value of >90% in detecting acute cholecystitis when stones are seen Pericholecystic fluid (in the absence of ascites) and gallbladder wall thickening to >4 mm (in the absence of hypoalbuminemia) are nonspecific findings but are suggestive of acute cholecystitis

EUS

Choledocholithiasis

Highly accurate for excluding or confirming stones in the BD Concordance of EUS with the ERCP diagnosis ≈95%; many studies suggest slightly higher sensitivity rates for EUS than for ERCP Specificity ≈97% Positive predictive value ≈99%, negative predictive value ≈98%, accuracy ≈97% With experienced operators, EUS can be used in lieu of ERCP to exclude BD stones, particularly when the clinical suspicion is low or intermediate Considered for patients with low to moderate clinical probability of choledocholithiasis Continued

38

Section I  n  Diagnostic Imaging

Table 1.1    Imaging Studies of the Biliary Tract—cont’d TECHNIQUE Oral cholecystography

CONDITION TESTED FOR Cholelithiasis

FINDINGS/COMMENTS Stones manifest as mobile filling defects in an opacified gallbladder Sensitivity and specificity exceed 90% when the gallbladder is opacified, but nonvisualization occurs in 25% of studies and can result from multiple causes other than stones Opacification of the gallbladder indicates cystic duct patency May be useful in the evaluation of acalculous gallbladder diseases such as cholesterolosis and adenomyomatosis

Cholescintigraphy (hepatobiliary scintigraphy; hydroxyiminodiacetic acid or diisopropyl iminodiacetic acid scan)

Acute cholecystitis

Assesses patency of the cystic duct A normal scan shows radioactivity in the gallbladder, BD, and small bowel within 30–60 minutes A positive result is defined as nonvisualization of the gallbladder, with preserved hepatic excretion of radionuclide into the BD or small bowel Sensitivity is ≈95% and specificity is ≈90%, with false-positive results seen in fasted critically ill patients With cholecystokinin stimulation, the gallbladder “ejection fraction” can be determined and may help evaluate patients with acalculous biliary pain A normal scan result virtually excludes acute cholecystitis

ERCP

Choledocholithiasis

ERCP is the standard diagnostic test for stones in the BD, with sensitivity and specificity of ≈95% Use of ERCP to extract stones (or at least drain infected bile) is life-saving in severe cholangitis and reduces the need for BD exploration at the time of cholecystectomy Recommended for patients with a high clinical probability of choledocholithiasis

Cholelithiasis

When contrast agent flows retrograde into the gallbladder, stones appear as filling defects and can be detected with a sensitivity rate of ≈80%, but US remains the mainstay for confirming cholelithiasis

Section I  n  Diagnostic Imaging

39

Table 1.1    Imaging Studies of the Biliary Tract—cont’d TECHNIQUE

CONDITION TESTED FOR

MRCP

Choledocholithiasis

FINDINGS/COMMENTS A rapid, noninvasive modality that provides detailed bile duct and pancreatic duct images equal to those of ERCP Sensitivity ≈93% and specificity ≈94%, comparable with those for ERCP Useful for examining nondilated ducts, particularly at the distal portion, which often is not well visualized by US Adjacent structures such as the liver and pancreas can be examined at the same time Recommended for patients with low to moderate clinical probability of choledocholithiasis

CT

Complications of gallstones

Not well suited for detecting uncomplicated stones but excellent for detecting complications such as abscess, perforation of gallbladder or BD, and pancreatitis Spiral CT may prove useful as a noninvasive means of excluding BD stones; some studies suggest improved diagnostic accuracy when CT is combined with an oral cholecystographic contrast agent

BD, Bile duct; ERCP, endoscopic retrograde cholangiopancreatography; EUS, endoscopic ultrasound; MRCP, magnetic resonance cholangiopancreatography; US, ultrasound. Feldman M, Friedman LS, Brandt LJ: Sleisenger and Fordtran’s gastrointestinal and liver disease, ed 10, Philadelphia, 2016, Elsevier.

 24.  Endoscopic Ultrasound (EUS) Indications

• Evaluation of choledocholithiasis; useful when CT and ultrasonography fail to show suspected CBD stones • Preoperative staging of esophageal and gastric malignancies (Fig. 1.33) • Detection of defects in internal and external sphincter in patients with fecal incontinence, detection of exophytic distal rectal tumors, fistula-in-ano, perianal abscess, rectal ulcer, and presacral cyst • Localization of insulinomas and other pancreatic endocrine tumors • Evaluation of submucosal lesions of the GI tract • Guidance for fine-needle aspiration of pancreatic cysts • Chronic pancreatitis: useful to delineate strictures and proximal dilation of CBD and intrahepatic biliary radicles • Useful for selecting patients who might benefit from ERCP and early stone extraction 

Strengths

• When used for evaluation of submucosal GI lesions, the sensitivity of EUS in determining the depth of tumor invasion is approximately 85% to 90%. • In fecal incontinence, EUS-detected sphincter disruption correlates well with pressure measurements and operative findings.

40

Section I  n  Diagnostic Imaging

A

B

C Fig. 1.33  (A) Endoscopic picture of malignant esophageal stricture. (B) Endoscopic ultrasound image showing T3 lesion. (C) Malignant celiac lymphadenopathy. (From Cameron JL, Cameron AM: Esophageal function test. In: Current surgical therapy, ed 10, Philadelphia, 2011, Saunders.) • EUS is less invasive than MRCP or ERCP and has a sensitivity and specificity of 90% to 100% for evaluation of choledocholithiasis. The major benefit of EUS in patients with a clinical suspicion of choledocholithiasis is the ability to avoid unnecessary ERCP and sphincterectomy. 

Weaknesses

• Can overestimate the extent of GI tumor invasion because of the presence of tissue inflammation and edema • Operator dependent; results may be affected by skill of technician 

Comments

• EUS combines ultrasonography and endoscopic evaluation. It involves visualization of the GI tract via a high-frequency ultrasound transducer placed through an endoscope. • Cost: $$$ 

25.  Video Capsule Endoscopy (VCE) Indications

• Determination of obscure source of GI bleeding • Diagnosis of Crohn disease in the small intestine • Detection of tumors and polyps in the small bowel • Detection of small intestinal ulcerations (Fig. 1.34) • Diagnosis of Meckel diverticulum • Diagnosis of small-bowel varices in patients with portal hypertension and obscure GI bleeding

Section I  n  Diagnostic Imaging

41

Fig. 1.34  Examples of small intestinal ulcerations found on capsule endoscopy. (Courtesy Dr. Laurel Fisher, University of Michigan.)

 Strengths

• Noninvasive • Ambulatory testing • Minimal or no patient discomfort • Able to visualize the entire small intestine • Does not require sedation or analgesia 

Weaknesses

• Cannot take biopsies • Can result in capsule retention (20%) and documented recent ventricular fibrillation or ventricular tachycardia, and obstructive hypertrophic cardiomyopathy. • Cost: $$$ 

3.  Cardiac MRI (CMR) Indications

• Evaluation of pericardial effusion • Constrictive pericarditis • Evaluation of distribution of hypertrophy in hypertrophic cardiomyopathy

52

Section I  n  Diagnostic Imaging Ammonia

Fluorodeoxyglucose

Apex

Anterior

Vertical Long-Axis View

Study 1

Study 2

L

Anterior

Base Apex

I Normal Ammonia Study 1

Apex

Study 1

Anterior

Fluorodeoxyglucose Study 2

Apex

Lateral Septal

Horizontal Long-Axis View

Study 2

Anterior

Base Apex

Vertical Long-Axis View

S

A

A

B

Apex

Study 2

Lateral Septal

Horizontal Long-Axis View

Study 1

Ischemia

Fig. 1.43  A positron emission tomography viability study. For each panel of four views, perfusion imaging with N-13-labeled ammonia uptake is on the left, and metabolic imaging with F-18 fluorodeoxyglucose (FDG) uptake is on the right. The upper row of each panel is the horizontal long-axis slice with the apex at the top, and the lower row is a vertical longaxis slice with the apex pointing to the left. The yellow and white areas are sites of maximal activity, and the blue areas are sites of minimal activity. The red areas indicate intermediate activity. (A) Normal images. (B) An example of ischemia and viable tissue.

Section I  n  Diagnostic Imaging Ammonia Apex

Study 1

Anterior

C

Fluorodeoxyglucose Apex

Lateral Septal

Study 2

Study 2

Anterior

Base Apex

Vertical Long-Axis View

Horizontal Long-Axis View

Study 1

53

Scarring

Fig. 1.43 cont’d (C) An example of myocardial scarring. Note the homogeneous uptake of both ammonia and FDG in the normal study. In the presence of ischemia (B), there is a mismatch (arrows), with decreased perfusion and augmented metabolic activity in the apex and the anterior wall. With scarring (C), there is equally decreased uptake of FDG and ammonia in the inferior and lateral walls. A, Anterior wall; I, inferior wall; L, lateral wall; S, septum. (From Sellke FW, del Nido PJ, Swanson SJ: Sabiston and Spencer surgery of the chest, ed 9, Philadelphia, 2016, Elsevier.) • Evaluation of right ventricular dysplasia • Thoracic aorta abnormalities (dissection, coarctation, aneurysm, hematoma) • Assessment of anatomy in congenital heart disease (intracardiac shunt, anomalous coronary arteries) • Imaging of intracardiac masses such as thrombi and tumors (atrial myxoma, rhabdomyosarcoma, metastatic disease) • Suspected cardiac involvement from sarcoidosis • Suspected cardiac hemochromatosis, amyloidosis • CAD (MI, myocardial ischemia): first-pass perfusion measurements for assessment of myocardial ischemia, dobutamine stress cine-MRI to detect stress-induced ischemia • Physiologic imaging (bulk flow in large vessels, pressure gradients across stenotic lesions, shunt fraction) • Quantified cavity volumes, EF, ventricular mass • Assessment of morphologic findings and wall motion abnormalities in cases in which echocardiography is not diagnostic (20% of echocardiography is not diagnostic because of insufficient image quality [e.g., patients with emphysema, obese patients]) • Assessment of bypass grafts (includes magnetic resonance angiography [MRA]) 

Strengths

• Noninvasive • No ionizing radiation • Superior image quality and flexibility in assessment of cardiac anatomy, coronary blood flow, and myocardial perfusion

54

Section I  n  Diagnostic Imaging Short Axis

VLA

HLA Stress

Rest

Diastole

Systole

Fig. 1.44  Stress and rest single-photon emission computed tomography (SPECT) studies (left two columns) in a normal patient, showing representative short-axis, vertical long-axis (VLA), and horizontal long-axis (HLA) images. Note the uniform uptake of Tc-99m sestamibi on both the stress and the rest tomograms, consistent with homogeneous regional myocardial blood flow. The right two columns show the end-diastolic and end-systolic images acquired during stress and demonstrate uniform systolic thickening in all myocardial segments. The left ventricular cavity size is greater on images acquired during diastole compared with systole, consistent with a normal left ventricular ejection fraction. The “brightness” of the images at end-systole correlates directly with the degree of systolic thickening. (From Goldman L, Bennet JC: Cecil textbook of medicine, ed 21, Philadelphia, 2000, Saunders.) • Images can be generated in any planar orientation • Less operator dependent than echocardiogram • Unlike echocardiography, images are not limited by an acoustic window 

Weaknesses

• Expensive • Needs cooperative patient • Time-consuming • Not readily available • Cannot be performed in patients with aneurysm clips that are not compatible with magnetic resonance or in patients with a pacemaker, cochlear implants, or metallic foreign body in the eyes; safe in women with IUDs, including copper ones, and in patients with surgical clips and staples • Suboptimal images in patients with irregular rhythm (e.g., atrial fibrillation, frequent ectopy) • Image distortion in the region immediately surrounding the prosthesis in patients with bioprosthetic and mechanical heart valves • Image distortion in patients with sternotomy wires and thoracic vascular clips 

Comments

• CMR is an excellent imaging technique for evaluation of the pericardium (Fig. 1.45) and pericardial effusions. It can also be used for imaging of thoracic aorta and great vessels (Fig. 1.46), cardiac tumors and masses, cardiomyopathies, and for quantitative assessment of ventricular volumes and mass. Its major limiting factor is its cost disadvantage compared with ultrasound. • Myocardial perfusion can be evaluated with MRI by giving an IV contrast agent (e.g., Gd-DPTA), which is taken up by viable myocardial cells concomitantly with dipyridamole or other pharmacologic stress agent.

Section I  n  Diagnostic Imaging

55

Fig. 1.45  Magnetic resonance imaging scan of constrictive pericarditis in rheumatoid arthritis. The dense white infiltrate between the pericardium and gray myocardium is pericardial fluid. (From Hochberg MC et al, editors: Rheumatology, ed 3, St. Louis, 2003, Mosby.) • Anxious patients (especially those with claustrophobia) should be premedicated with an anxiolytic agent, and their imaging should be done with “open MRI” whenever possible. • Cost: $$$$ 

4. Multidetector CT Scan (Non-contrast CT Scan for Coronary Artery Calcium Scoring) Indications

• This test can be used to identify and measure coronary artery calcifications. Calcification levels can be related to the extent and severity of underlying atherosclerosis and can potentially improve cardiovascular risk prediction. In clinically selected intermediate-risk patients, it may be reasonable to measure the atherosclerosis burden using multidetector CT (Fig. 1.47) to refine clinical risk prediction and to select patients for more aggressive target values for lipid-lowering therapies. • Coronary calcium measurements are not indicated in patients at low risk of cardiovascular disease. The CAC is estimated from noncontrast CT images. Normal coronary arteries do not have plaques or calcium, and the normal score is 0. A CAC score of 300 or higher or 75th percentile or higher for age, sex, and ethnicity is considered a high risk. According to the recent ACC/AHA guidelines, CAC is most appropriate among adults with an estimated 10-yr ASCVD risk 75th percentile for age, sex, and ethnicity is considered high risk and would justify revising a patient’s risk upward. • Multidetector CT is useful in excluding coronary disease in selected patients in whom a false-positive or inconclusive stress test is suspected • Coronary calcium assessment may be considered in symptomatic patients to determine the cause of cardiomyopathy 

Strengths

• Speed • Safety (less invasive than angiography) • Lower cost than angiography • High sensitivity and negative predictive value 

56

Section I  n  Diagnostic Imaging

T S A

A P

P

LAA

LA RA

LV

A

I

B

A

P LA RV

LV

C Fig. 1.46  Normal radiographic anatomy, magnetic resonance images. (A) Coronal section at the level of the aortic valve. The right border of the cardiac silhouette is formed by the superior vena cava (S) and the right atrium (RA). The arrow indicates the cavalatrial junction. The lower portion of the left cardiac border is formed by the left ventricle (LV). A, Ascending aorta; P, main pulmonary artery. (B) Coronal section at the level of the left atrium. The upper portion of the left cardiac border is formed by the aorta (A), main pulmonary artery (P), and left atrial appendage (LAA); see arrow. I, Inferior vena cava; LA, left atrium; T, trachea. (C) Sagittal section near the midline. The right ventricle (RV) forms the anterior surface of the heart, which abuts the sternum. The pulmonary artery (P) extends upward and posteriorly from the ventricle. The posterior border of the heart is formed by the left atrium (LA) and left ventricle (LV). The aorta (A) is behind the heart. (From Goldman L, Schafer AI: Radiology of the heart. In: Goldman’s Cecil medicine, ed 24, Philadelphia, 2012, Saunders.)

Weaknesses

• Limited to patients with regular rhythm and slow rates (the image quality is inversely related to the heart rate) • Poor images in morbidly obese patients • Inaccurate visualization of the coronary artery within a stent • Coronary calcification interferes with images obtained by CT; decreased diagnostic accuracy in older patients because of the prevalence and severity of coronary calcifications with increasing age

Section I  n  Diagnostic Imaging

57

A

B Fig. 1.47  Non-contrast-enhanced computed tomography axial slices through the heart at two locations for coronary calcium scoring as risk assessment in an asymptomatic patient. (A) The slice includes the left anterior descending artery with extensive calcification in its proximal portion (arrow). (B) The slice includes the right coronary artery with proximal spotty calcification (arrow). This patient’s calcium score was 457, putting him in a higher risk group regardless of his Framingham risk score. (From Goldman L, Shafer AI: Goldman’s Cecil medicine, ed 26, Philadelphia, 2020, Elsevier.)

• Insufficient breath-holding or slightly different positions of the heart at subsequent heartbeats are artifacts that can be more difficult to control • High radiation exposure 

Comments

• If calcification is detected in the coronary arteries, a “calcium score” is computed for each of the coronary arteries based on the size and density of the regions identified to contain calcium. Although the calcium score does not correspond directly to narrowing in the artery caused by atherosclerosis, it correlates with the severity of coronary atherosclerosis present. For example, a calcium score of 1 to 10 indicates minimal plaque burden and low likelihood of CAD, whereas a score of 101 to 400 indicates moderate plaque burden and high likelihood of moderate nonobstructive

58

Section I  n  Diagnostic Imaging

CAD. Calcium scores of more than 300 are associated with an increased risk of MI and cardiac death at every risk level. The calcium score can also be used to compare the patient’s results with those of others of the same age and gender to determine a percentile ranking. • A multidetector CT scan is a reasonable test to assess patients who have equivocal treadmill or functional test results and to assess patients with chest pain who have equivocal or normal echocardiography findings and negative cardiac enzyme results. • Research data is currently insufficient on the use of serial cardiac CT in assessing subclinical atherosclerosis over time and in detecting noncalcified plaque. • Cost: $$$$ 

5.  Transesophageal Echocardiogram (TEE) Indications

• Suspected subacute bacterial endocarditis (SBE) (Fig. 1.48) • Evaluation of prosthetic valves • Evaluation of embolic source • Suspected aortic dissection • Identification of intracardiac shunts • Visualization of atrial thrombi • Diseases of aorta • Intracardiac mass • Intraoperative use in valve repair, congenital heart surgery, repair of hypertrophic obstructive cardiomyopathy

 Strengths

• Image quality superior to that of transthoracic echocardiogram (TTE) • No ionizing radiation 

Ao LV Veg. LA

Fig. 1.48  Native aortic valve endocarditis in a patient with severe aortic regurgitation and cardiogenic shock. There is a large, mobile vegetation that is adherent to the aortic valve and that prolapses into the LV outflow tract (arrow). Ao, Aorta; LA, left atrium; LV, left ventricle; Veg., vegetation. (From Sellke FW, del Nido PJ, Swanson SJ: Sabiston and Spencer surgery of the chest, ed 9, Philadelphia, 2016, Elsevier.)

Section I  n  Diagnostic Imaging

59

Weaknesses

• Invasive • Requires patient preparation, monitoring • Complication rate of 0.2% to 0.5% (e.g., esophageal trauma, aspiration, cardiac dysrhythmias, respiratory depression secondary to sedation) 

Comments

• TEE is performed by mounting an ultrasound transducer at the end of a flexible tube to image the heart from the esophagus (Fig. 1.49). • Useful modality for assessing valvular pathologic findings and diseases of the aorta • Cost: $$$ 

6.  Transthoracic Echocardiography (TTE) Indications

• Evaluation of heart murmur • Chest pain • Evaluation of EF • Systemic embolus • Syncope of suspected cardiac etiologic factors • Suspected endocarditis • Pericardial effusion • Abnormal heart size on chest film • Atrial septal defect (ASD) • Ventricular septal defect (VSD) • Valvulopathy • Cardiomyopathy • Guidance of needle placement for pericardiocentesis 

Strengths

• Noninvasive • Fast • Can be performed at bedside

Fig. 1.49  Transesophageal echocardiography. Diagram illustrates location of the transesophageal endoscope within the esophagus. (From Pagana KD, Pagana, TJ: Mosby’s diagnostic and laboratory test reference, ed 8, St. Louis, 2007, Mosby.)

60

Section I  n  Diagnostic Imaging Suprasternal

Subcostal

Parasternal Apical

Fig. 1.50 Standard acoustic windows for transthoracic echocardiography. Parasternal and apical windows are obtained with the patient in a left lateral position. The subcostal window is obtained with the patient supine and legs flexed, to relax the abdominal wall. The suprasternal notch window is obtained with the patient’s head tilted to the side to aid transducer placement. (From Otto CM, Schwaegler RG, Freeman RV: Echocardiography review guide, Philadelphia, 2011, Saunders, Fig. 2.6.) • No need for patient preparation, premedication, or monitoring • No ionizing radiation 

Weaknesses

• Less sensitive than TEE for SBE, prosthetic valves • Limited use in obese patients, patients with chronic obstructive pulmonary disease (COPD), and patients with chest deformities • Resting echocardiogram not sensitive for detecting CAD 

Comments

• Fig. 1.50 demonstrates standard acoustic windows for transthoracic echocardiography. Figs. 1.51 and 1.52 illustrate the four basic image planes used in TTE. Echocardiography zones are shown in Fig. 1.53. Table 1.3 summarizes key echocardiographic findings and limitations of echocardiography in various disorders. • TEE is preferred over TTE in evaluation of prosthetic valve, embolic source, and SBE. • Doppler echocardiogram is useful for evaluation of shunts and stenotic or regurgitant valves and for measurement of cardiac output (Tables 1.4 to 1.6). • Contrast echocardiography uses commercially produced microbubbles or agitated saline and air to obtain a better definition when evaluating for intracardiac shunts. • Fig. 1.54 shows the echocardiographic appearance of hypertrophic cardiomyopathy. • Cost: $$ 

7.  Intravascular Ultrasound (IVUS) Indications

• Left main CAD evaluation when doubt persists about the severity of stenosis on angiography • Discordance between symptoms or noninvasive test results and coronary angiogram • Ambiguous lesions (ostial lesion, bifurcation lesion, aneurysm, hazy lesion) • Transplant vasculopathy • In-stent restenosis or thrombosis • Stent implantation in medium-sized (2.5–3.25 mm) arteries • Unsatisfactory angiographic or symptomatic results of percutaneous coronary interventions 

Section I  n  Diagnostic Imaging Right ventricular outflow tract

61

Aorta Left atrium

Left ventricle

Left ventricle

Left atrium Left atrium auricle

Left ventricle

Right ventricle

Left ventricle

Right ventricle Right atrium

Descending aorta Left atrium

Fig. 1.51  The four basic image planes used in transthoracic echocardiography. A parasternal transducer position or “window” is used to obtain long- and short-axis views. The long-axis view extends from the left ventricular apex through the aortic valve plane. The short-axis view is perpendicular to the long-axis view, resulting in a circular view of the left ventricle. The transducer is placed at the ventricular apex to obtain the two-chamber and four-chamber views, each of which is approximately a 60-degree rotation from the longaxis view and perpendicular to the short-axis view. The four-chamber view includes both ventricles and both atria. The two-chamber view includes the left ventricle and left atrium; sometimes the atrial appendage is visualized. (From Otto CM: Textbook of clinical echocardiography, ed 4, Philadelphia, 2009, Elsevier Saunders; 32, Fig. 2.1.)

Strengths

• IVUS provides cross-sectional images of both the arterial wall and lumen with excellent resolution, reveals the diffuse nature of atherosclerosis and the involvement of reference segments, and takes into account vessel wall remodeling 

Weaknesses

• Invasive • Requires full anticoagulation • Coronary spasm occurs in 2% of patients (usually responds to intracoronary nitroglycerin) 

Comments

• IVUS imaging is conducted by experienced interventional physicians in the cardiac catheterization laboratory. A 0.0014-inch guidewire is first advanced to the distal segment of the artery of interest. IVUS imaging is then performed with 2.5- to 3.5-French catheters with miniaturized ( 30 g/day

Image pancreas Secretin test

Proximal

Suspicion of rapid transit (altered gastric, small bowel, esophageal anatomy)

Small bowel barium study for transit time

Suspicion of bacterial overgrowth (elderly, DM, small bowel stricture or dysmotility) (see Box 3.6)

Suspicion of mucosal disease (weight loss, multiple nutrient malabsorption) Distal CT or MR enterography

Fig. 3.136  Approach to the diagnosis of malabsorption. CT, Computed tomography; DM, diabetes mellitus; MR, magnetic resonance; PCR, polymerase chain reaction. (From Goldman L, Shafer AI: Goldman-Cecil medicine, ed 26, Philadelphia, 2020, Elsevier.)

Section III n Diseases and Disorders

393

 Tests to Establish the Cause of Malabsorption Based on

BOX 3.6   Main Symptoms

Weight Loss, Osteomalacia or Osteopenia, Diarrhea, Suspected Steatorrhea, or Deficiency of Fat-Soluble Vitamins First-Line Tests





• Abdominal and small-intestinal US • Chymotrypsin or elastase concentration in stool • EGD with small-intestinal biopsies • Endomysial or tissue transglutaminase antibodies • Laboratory tests (CBC, white blood cell differential, cholesterol, TGs, electrolytes, calcium, magnesium, serum ALT, AST, AP, bilirubin levels, prothrombin time, serum albumin level, erythrocyte sedimentation rate and C-reactive protein, TSH) • Ova, parasites, calprotectin and leukocytes in stool  Second-Line Tests



• Abdominal CT, MRI • Endoscopic examination of the terminal ileum, including ileal biopsies • Enteroscopy, including biopsies • ERCP/MRCP • More extensive laboratory investigation (immunoglobulins, HIV ELISA, antinuclear antibodies, ferritin, food allergen–specific IgE, ACTH cortisol, chromogranin A, gastrin, urinary 5-HIAA) • Quantitative fecal fat • Quantitative small-intestinal culture or breath tests for small intestinal bacterial overgrowth (SIBO) • Small-bowel series/small-bowel MRI • Special staining of small-intestinal biopsies (e.g., Congo red for amyloid, PAS for Whipple disease) • Therapeutic trial of pancreatic enzymes, antibiotics (tetracycline, metronidazole), cholestyramine, or a gluten-free diet • Video capsule endoscopy  Tests in Unusually Difficult Cases (Third-Line Tests)





• Mesenteric angiography • Antienterocyte antibodies • EUS • MRA • PET • Serum or plasma glucagon, somatostatin • Somatostatin (octreotide) scan • Special tests of intestinal biopsies (e.g., flow cytometry of intraepithelial lymphocytes for lymphoma and refractory celiac disease, PCR for Tropheryma whipplei or other infective organisms, chromogranin A stain for enteroendocrine cells) • Spiral CT of the pancreas • Tests for bile acid malabsorption • Tube test for exocrine pancreatic secretion (secretin, CCK, or Lundh test)  Bloating, With or Without Diarrhea First-Line Tests



• Fructose H2 breath test • Lactose H2 breath test • Lactose tolerance test 

394

Section III n Diseases and Disorders  Tests to Establish the Cause of Malabsorption Based on

BOX 3.6   Main Symptoms—cont’d Second-Line Tests



• Chymotrypsin or elastase concentration in stool • EGD with duodenal biopsies • Endomysial or tissue transglutaminase antibodies • Genetic testing for hypolactasia • Quantitative small-intestinal culture or breath tests for SIBO • Stool pH (in patients with diarrhea)  Anemia and Suspected Malabsorption Microcytic or Hypochromic Anemia (low MCV, MCH)



• EGD with duodenal biopsies • Endomysial and tissue transglutaminase antibodies • Iron, ferritin, and transferrin in serum • Ova and parasites in stool • Video capsule endoscopy • Calprotectin • FOBT  Macrocytic Anemia (high MCV, MCH) First-Line Tests



• Folic acid in serum or red blood cells • Vitamin B12 in serum 



• CT, small-bowel series, enteroclysis, video capsule endoscopy • EGD with gastric and duodenal biopsies • Endomysial and tissue transglutaminase antibodies • Evaluation of ileum (e.g., colonoscopy to ileum with biopsy, balloon enteroscopy with biopsy) • Ova and parasites in stool • Quantitative small-intestinal culture or breath tests for SIBO • Calprotectin • Schilling test (with and without intrinsic factor) 



• EGD with duodenal biopsies • Endomysial or tissue transglutaminase antibodies

Second-Line Tests in Cases of Vitamin B12 Deficiency

Second-Line Tests in Cases of Folate Deficiency

AP, Alkaline phosphatase; CBC, complete blood cell count; FOBT, fecal occult blood test; 5-HIAA, 5-hydroxyindoleacetic acid; IgE, immunoglobulin E; MCH, mean corpuscular hemoglobin; MCV, mean corpuscular volume; PAS, periodic acid– Schiff; TG, triglycerides; TSH, thyroid-stimulating hormone. From Feldman M, Friedman LS, Brandt LJ: Sleisenger and Fordtran’s gastrointestinal and liver disease, ed 10, Philadelphia, 2016, Saunders.

Section III n Diseases and Disorders

395

93.  Meningioma (Fig. 3.137) Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • MRI or CT of brain with contrast (Fig. 3.138A and B)

Best Test(s) • None

Ancillary Tests • Cerebral angiography (see Fig. 3.138C)  

Ancillary Tests • None

Positive (contrast-enhancing lesion) Suspected meningioma

CT of brain with contrast

Cerebral angiogram if surgery is contemplated Positive

Equivocal

MRI of brain with contrast Negative

Fig. 3.137  Diagnostic algorithm.

B

A

C Fig. 3.138  Subfrontal meningioma. Computed tomography (CT) scan before (A) and after (B) intravenous contrast medium and lateral projection of common carotid arteriogram (C). There is a large, circumscribed mass in the anterior cranial fossa that is isodense to normal gray matter, contains foci of calcification centrally, and enhances homogeneously. There is edema in the white matter of both frontal lobes and posterior displacement and splaying of the frontal horns of the lateral ventricles. On the arteriogram (C), the mass is delineated by a tumor blush, and the anterior cerebral arteries are displaced posteriorly, mirroring the mass effect seen on CT. The ophthalmic artery is enlarged as its ethmoidal branches supply the tumor (arrow). (From Grainger RG, Allison DJ, Adam A, et al, editors: Grainger and Allison’s diagnostic radiology, ed 4, Philadelphia, 2001, Churchill Livingstone.)

396

Section III n Diseases and Disorders

94.  Mesenteric Ischemia (Fig. 3.139) Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • CT of abdomen with IV contrast (Fig. 3.140): may reveal bowel wall thickening, venous dilation, venous thrombus

Best Test(s) • CBC with differential • Serum electrolytes (metabolic acidosis is indicative of possible bowel infarction) • Lactic acid

Ancillary Tests • Angiography if CT is inconclusive • Abdominal plain radiograph (generally nonspecific)

Ancillary Tests • Serum amylase, lipase • Hypercoagulopathy workup (e.g., PT (INR), PTT, platelets, protein C, protein S, antithrombin III) • d-dimer

 

Diagnostic Suspected mesenteric ischemia

CT of abdomen and laboratory evaluation Inconclusive

Angiography

Fig. 3.139  Diagnostic algorithm.

Fig. 3.140  Computed tomography scan after administration of oral and intravenous contrast in a patient with an embolism to the superior mesenteric artery and ischemia of the small bowel and right colon. The arrow points to the embolus in the superior mesenteric artery. (From Vincent JL, Abraham E, Moore FA, et al: Textbook of critical care, ed 6, Philadelphia, 2011, Saunders.)

Section III n Diseases and Disorders

397

95.  Mesothelioma (Fig. 3.141) Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • CT of chest with IV contrast after initial abnormalities noted on chest x-ray (Fig. 3.142)

Best Test(s) • Pleural biopsy

Ancillary Tests • CT of abdomen with IV contrast and bone scan to assess extent of disease

Ancillary Tests • Cytologic examination from diagnostic thoracentesis is generally inadequate for diagnosis • PFTs

  Abnormal chest x-ray revealing pleural plaques/ calcifications and/or pleural effusion

CT of chest

CT of abdomen and bone scan for staging

Tissue diagnosis (thoracoscopy, pleuroscopy, and open-lung biopsy are useful in obtaining adequate tissue samples for diagnosis)

Staging and preoperative evaluation PFTs

Fig. 3.141  Diagnostic algorithm.

A

B

Fig. 3.142  Malignant pleural thickening. Posteroanterior (A) and lateral (B) chest radiographs. Malignant pleural thickening is characteristically lobulated and nodular. The extensive right-sided disease in this patient was caused by mesothelioma. Notice the extension of the tumor into the fissure. (From Grainger RG, Allison DJ, Adam A, et al, editors: Grainger and Allison’s diagnostic radiology, ed 4, Philadelphia, 2001, Churchill Livingstone.)

Section III n Diseases and Disorders

398

96.  Metabolic Acidosis (Fig. 3.143) Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • None

Best Test(s) • Serum electrolytes • ABGs

Ancillary Tests • Chest radiograph

Ancillary Tests • BUN, creatinine, glucose • Determination of anion gap: + − AG = Na − ( Cl + HCO3−) • Lactate level • Urine electrolytes • Ethylene glycol, methanol, ethanol (if osmolar gap >12)

 

METABOLIC ACIDOSIS

Anion gap >10

Yes

No

RTA Diarrhea Ileostomy Diabetes Excessive NaCl

Hyperchloremic acidosis

Type B1 Sepsis Malignancy Hepatic disease Beri-beri Pheochromocytoma Alcoholic ketoacidosis Short bowel syndrome

Type B2 Biguanides, streptozocin Fructose, sorbitol Sodium nitroprusside, Terbutaline, isoniazid Methanol, ethelene glycol

No

Lactate >2 mmol/L

Yes

No

Ketones

Yes Yes

Yes

Tissue hypoxia

Lactic acidosis

No

Type A Cardiogenic shock Hypovolemic shock Profound hypoxemia Profound anemia Seizures CO poisoning

No Glucose high No

Diabetic ketoacidosis Starvation ketosis Alcoholic ketoacidosis

No

RENAL FAILURE

No

Decreased AG Hypoproteinemia Myeloma Inc, Ca, Mg Br (pseudohyper Cl)

OSMOLAR GAP >12

Yes

Ethylene glycol Methanol Ethanol

No

Aspirin Paraldehyde

Increased AG Alkemia Carbenicillin, etc.

Fig. 3.143  Diagnostic approach to metabolic acidosis. (From Vincent JL, Abraham E, Moore FA, et al: Textbook of critical care, ed 6, Philadelphia, 2011, Saunders.)

Section III n Diseases and Disorders

399

97.  Metabolic Alkalosis (Fig. 3.144) Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • None

Best Test(s) • ABGs • Urine electrolytes, serum electrolytes

Ancillary Tests • Chest radiograph

Ancillary Tests • BUN, creatinine • Urine potassium • Plasma renin • Plasma cortisol

  Urine Cl– 20 mEq/L

Check urine chloride [Cl–]

Chloride-responsive alkalosis

Chloride-unresponsive alkalosis

• Gastric fluid loss • Nonreabsorbable anion delivery • Diuretics • Posthypercapnia • Villous adenoma • Congenital chloridorrhea

Check urine potassium [K+] Urine K+ >30 mEq/dL

Urine K+ 50, history of tobacco use, hemoptysis, voice hoarseness)

Suspected infectious process

Thyroid/parathyroid mass

Presence of alarm signs

CBC with differential, monospot, throat C&S

TSH, serum calcium, ultrasound of thyroid

CT or MRI of neck, chest x-ray

Diagnostic

Negative

Normal

Diagnostic

CT scan

Diagnostic

Negative Fig. 3.153  Diagnostic algorithm.

ENT referral for additional evaluation and biopsy

Section III n Diseases and Disorders

407

104.  Neck Pain (Fig. 3.154) Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • MRI C-spine

Best Test(s) • None

Ancillary Tests • X-ray C-spine (initial test) • EMG

Ancillary Tests CBC, ESR

  Neck pain

History clinical exam

Axial neck pain

Conservative care Soft collar, medications, PT

Radiculopathy

No improvement

Negative findings Continue conservative treatments

Myelopathy

Suspected neoplasm or infection

Radiologic studies

Rigid collar Spine precautions

X-ray, CT, MRI, bone scan

Mild findings

Severe findings

Neural compression Bone lesion Deformity

Neural compression Bone lesion Deformity

Neurodiagnostics Conservative treatments with negative results

Trauma

EMG, NCS, SSEP

Evidence of nerve or cord compression

Request spine surgeon consult

Fig. 3.154  Algorithm of neck pain. CT, Computed tomography; EMG, electromyogram; MRI, magnetic resonance imaging; NCS, nerve conduction study; PT, physical therapy; SSEP, somatosensory evoked potentials. (From Firestein GS et al: Kelley’s textbook of rheumatology, ed 9, Philadelphia, 2013, Saunders.)

408

Section III n Diseases and Disorders

105.  Neuropathy (Fig. 3.155) Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • None

Best Test(s) • ENMG of affected limb

Ancillary Tests • Chest radiograph (useful to r/o sarcoidosis, lung carcinoma) • Plain bone films in suspected trauma

Ancillary Tests • CBC, glucose, electrolytes, ALT, AST, calcium, magnesium, phosphate • Heavy metal screening in suspected toxic neuropathy • Lyme disease serologic testing in endemic areas or in patients with suggestive history and physical examination • TSH, B12, folate level • HIV in patients with risk factors

  History+Physical Exam ENMG

Demyelinating

Symmetrical

Acute AIDP Diphtheria

Chronic CMT1

Axonal

Asymmetrical

Acute AIDP

Chronic CIDP a-MAG

Symmetrical

Acute AMAN AMSAM

Chronic Diabetic CIP HIV Meds/Toxins

Asymmetrical

Acute Vasculitic Diabetic

Chronic MMN

Fig. 3.155  A systematic approach to evaluating neuropathy. The diseases listed are examples of neuropathies associated with specific neurophysiologic and clinical findings. Diabetic distal, predominantly sensory neuropathies are manifested as chronic axonal neuropathies; acute asymmetric neuropathies can also occur with diabetes. Most neuropathies caused by toxins or as side effects of medication are chronic symmetric axonal neuropathies. Acute inflammatory demyelinating polyradiculoneuropathy (AIDP), acute motor axonal neuropathy (AMAN), and acute motor and sensory axonal neuropathy (AMSAN) are subtypes of Guillain-Barré syndrome. α-MAG, Anti–myelin-associated glycoprotein; CIDP, chronic inflammatory polyradiculoneuropathy; CIP, chronic illness polyneuropathy; CMT1, Charcot-Marie-Tooth disease type 1, a genetic disorder; ENMG, electroneuromyography; HIV, human immunodeficiency virus–related neuropathy; MMN, multifocal motor neuropathy. (Modified from Goldman L, Schafer AI: Goldman’s Cecil medicine, ed 25, Philadelphia, 2015, Saunders.)

Section III n Diseases and Disorders

409

106.  Neutropenia (Fig. 3.156) Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • None

Best Test(s) • Bone marrow examination

Ancillary Tests • CT of abdomen and and pelvis with IV contrast

Ancillary Tests • CBC with differential (Table 3.22) • HIV • Blood culture × 2, urine C&S • B12 level, folate

  Neutropenia

Rule out drug-induced, infectious process (CBC, HIV, blood cultures, urine cultures)

Splenomegaly on exam

Evaluation of peripheral smear for polysegmented neutrophils

Rule out hypersplenism, sequestration Diagnostic

CT of abdomen

Absent

Present

Negative

Bone marrow exam

Serum B12, serum folate levels

Fig. 3.156  Diagnostic algorithm.

410

Section III n Diseases and Disorders

Table 3.22    Differential Diagnosis of Neutropenia Congenital Neutropenia • Ethnic and benign familial (constitutional) neutropenia • Severe congenital neutropenia • Autosomal dominant (ELANE mutation) • Autosomal recessive (Kostmann syndrome; HAX2 mutation) • X-linked (WASP mutation) • Other rare defects (G-CSFR mutation, unknown) • Cyclic neutropenia • Shwachman-Diamond syndrome • Fanconi anemia • Dyskeratosis congenita • Glycogen storage disease type Ib • Myelokathexis • Chédiak-Higashi syndrome • Griscelli syndrome type II • Hermansky-Pudlak syndrome II • Barth syndrome Acquired Neutropenia • Infection • Postinfection • Drug induced • Immune neutropenia • Primary immune neutropenia • Secondary to autoimmune disease • Rheumatoid arthritis • Felty syndrome • Large granular lymphocyte disease • Systemic lupus erythematosus • Granulomatosis with polyangiitis (formerly Wegener granulomatosis) • Hyperthyroidism • Pure white cell aplasia associated with thymoma • Large granular lymphocyte disease (independent of rheumatoid arthritis) • Primary bone marrow failure • Aplastic anemia • Myelodysplastic syndrome • Acute leukemia • Margination and hypersplenism • Vitamin and mineral deficiencies (including B12, folate, copper) • Chronic idiopathic neutropenia in adults (CINA) ELANE, Neutrophil elastase; G-CSFR, granulocyte colony-stimulating factor receptor; WASP, Wiskott-Aldrich syndrome protein. From Goldman L, Shafer AI: Goldman-Cecil medicine, ed 26, Philadelphia, 2020, Elsevier.

Section III n Diseases and Disorders

411

107.  Osteomyelitis (Fig. 3.157) Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • MRI of affected bone with contrast (Fig. 3.158)

Best Test(s) • Bone culture after surgical debridement

Ancillary Tests • Three-phase bone scan with Tc-99m MDP (useful if MRI is contraindicated or is not readily available) • Doppler study of affected extremity (useful for determining vascular patency in selected patients [e.g., diabetics]) • Conventional radiograph of affected bone (initial imaging test)

Ancillary Tests • ESR, CRP • CBC with differential • Blood culture × 2

  Suspected osteomyelitis based on physical exam, plain bone x-rays

MRI or bone scan of affected bone Surgical débridement, Gram stain, and bone cultures Ancillary lab tests

Fig. 3.157  Diagnostic algorithm.

Fig. 3.158  Vertebral osteomyelitis. A sagittal contrast-enhanced conventional spin-echo MRI scan (T1-weighted) demonstrates a posteriorly located epidural abscess at the L4– L5 vertebral level with an enhancing rim and displacement of the nerve roots anteriorly. (Courtesy Dr. Joseph Mammone. From Cohen J, Powderly WG: Infectious dis­ eases, ed 2, St. Louis, 2004, Mosby.)

412

Section III n Diseases and Disorders

108.  Pancreatic Mass (Fig. 3.159) Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • High-resolution CT of pancreas with IV contrast (Fig. 3.160)

Best Test(s) • Ultrasound-guided needle biopsy

Ancillary Tests • ERCP • EUS • MRCP • MRI pancreas (Table 3.23)

Ancillary Tests • Serum amylase, lipase • Alkaline phosphatase, ALT • Serum calcium

  Tissue diagnosis with needle biopsy using endoscopic ultrasound or CT

Abnormal Suspected pancreatic lesion

CT of pancreas

Negative Equivocal

Endoscopic ultrasound

MRI Positive

ERCP with biopsy if obstruction is present

Fig. 3.159  Diagnostic algorithm.

Fig. 3.160 Pancreatic carcinoma on computed tomography scan. (From Talley NJ, Mar­tin CJ: Clinical gastroenterology, ed 2, Sidney, 2006, Churchill Livingstone.)

Male predominance

Third to fifth decade

Common

Abdominal pain or mass effect

Unilocular, homogeneous, no solid component, findings of associated chronic pancreatitis

Common

Thin, clear to dark

High

Low

Inflammatory cells

Negative

None

Drainage (endoscopic, surgical, or percutaneous)

Gender distribution

Age at presentation

History of acute or chronic pancreatitis

Symptoms

Imaging characteristics (CT, MRI, or EUS)

Communication with the pancreatic duct

Fluid characteristics

Amylase level in the fluid

CEA level in the fluid

Cytology of the fluid or wall

DNA analysis

Malignant potential

Therapy

Resection

Moderate

High DNA amount or high-amplitude allelic loss, K-ras mutations in 50%

Mucinous epithelial cells or malignant cells

High (>192 ng/mL)

Low

Thick and viscous; may not be able to be aspirated

None

Unilocular or multilocular with septations, mural nodules, occasional calcifications in wall

Asymptomatic; less commonly abdominal pain or mass effect

Rare

Fifth to seventh decade

Female predominance

MUCINOUS CYSTIC NEOPLASM

Resection (main duct type) Close monitoring or resection (branch duct type)

High (main duct type) Low to moderate (branch duct type)

High DNA amount or high-amplitude allelic loss; KRAS mutations in 50%

Mucinous epithelial cells or malignant cells

High (>192 ng/mL)

Variable

Thick and viscous; may not be able to be aspirated

Common

Dilated main pancreatic duct (main duct type) Dilated side branches or cavity (side branch type)

Asymptomatic; less commonly abdominal pain, steatorrhea or weight loss

Occasional

Variable, usually fifth to seventh decade

Equal

INTRADUCTAL PAPILLARY MUCINOUS NEOPLASM

From Feldman M, Friedman LS, Brandt LJ: Sleisenger and Fortran’s gastrointestinal and liver disease, ed 10, Philadelphia, 2016, Elsevier.

PSEUDOCYST

FEATURE

Table 3.23    Features That Distinguish a Pseudocyst From the More Common Cystic Pancreatic Neoplasms

Observation unless the patient is very symptomatic or the diagnosis is uncertain

Very low

Usually negative

Cuboidal cells without mucin

Low

Low

Thin, clear

None

Microcystic, honeycomb appearance

Usually asymptomatic

Rare

Variable, usually fifth to seventh decade

Female predominance

SEROUS CYSTADENOMA

414

Section III n Diseases and Disorders

109.  Pancreatitis, Acute (Fig. 3.161) Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • CT of abdomen with IV contrast (Fig. 3.162); CT can also be used to assess severity of acute pancreatitis (Table 3.24)

Best Test(s) • Serum lipase • Serum amylase Ancillary Tests • Serum trypsin level and urinary trypsinogen level (sensitive tests, but not readily available) • ALT, AST, serum calcium, glucose, electrolytes, alkaline phosphatase, but not readily available • CBC, urinalysis • ABGs

Ancillary Tests • Ultrasound of abdomen when gallstone pancreatitis is suspected • MRCP (>90% sensitivity for choledocholithiasis) • Endoscopic ultrasound (useful to identify anatomic abnormalities and good sensitivity for small gallstones [≤5 mm]) • ERCP useful for biliary sphincterotomy and stone removal in retained bile duct stone • Abdominal plain film (often performed as initial imaging test in acute setting) • Chest radiograph   Lab evaluation

Suspected pancreatitis

CT of abdomen if diagnosis is in question or to assess degree of severity

Abnormal Abdominal plain film

Fig. 3.161  Diagnostic algorithm. Ant

F F Panc Panc Panc

C GB R

Ant

F Ao

L

F

C F

C R L

F

Panc

F Ao

K

K

A

F

C F F

K

B

Fig. 3.162  Acute pancreatitis. (A) A computed tomography scan in this young woman with hyperlipidemia shows the body of the pancreas (Panc) and surrounding fluid (F). The liver (L), kidney (K), gallbladder (GB), and colon (C) also are identified. Another image in the same patient obtained slightly more inferiorly (B) shows a marked amount of fluid (F) around the uncinate portion of the pancreas (Panc) and fluid extending around into the left paracolic gutter with associated thickening of Gerota’s fascia. Ao, Aorta. (From Mettler FA: Essentials of radiology, ed 3, Philadelphia, 2014, Saunders.)

Section III n Diseases and Disorders

415

Table 3.24    Scoring Systems to Assess Severity of Acute Pancreatitis DEFINITION OF SEVERE PANCREATITIS

SYSTEM

CRITERIA

Ranson

At admission: Age >55 years WBC >16,000/μL Glucose >200 mg/dL LDH >350 IU/L AST >250 IU/L Within next 48 h: Decrease in hematocrit by >10% Estimated fluid sequestration of >6 L Serum calcium 4 mmol/L

Total score ≥3

APACHE-II

Multiple clinical and laboratory factors. Calculator available at https://star.org/scores2/ apachw22.php

Total score ≥8

BISAP

BUN >25 mg/dL Impaired mental status Presence of SIRS Age >60 years Pleural effusion

Total score >2

CT

A: Normal pancreas B: Focal or diffuse enlargement of pancreas C: Grade B plus pancreatic and/or peripancreatic inflammation D: Grade C plus a single fluid collection E: Grade C plus two or more fluid collections or gas in pancreas

Grade >C

CT severity index

CT grade A=0 B=1 C=2 D=3 E=4 Plus necrosis grade No necrosis = 0 50% necrosis = 6

Score >5

APACHE, Acute Physiology and Chronic Health Evaluation; AST, aspartate aminotransferase; BISAP, Bedside Index of Severity of Acute Pancreatitis; BUN, blood urea nitrogen; CT, computed tomography; LDH, lactate dehydrogenase; PaO2, partial pressure of oxygen; SIRS, systemic inflammatory response syndrome; WBC, white blood count. From Goldman L, Schafer AI: Goldman’s Cecil medicine, ed 25, Philadelphia, 2015, Saunders.

416

Section III n Diseases and Disorders

110.  Parapharyngeal Abscess (Fig. 3.163) Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • CT of soft tissues of neck with IV contrast (Fig. 3.164)

Best Test(s) • None

Ancillary Tests • Lateral soft tissue radiograph of neck (often initial study) • MRI of neck

Ancillary Tests • CBC with differential • Throat C&S • Blood cultures

  Ancillary lab tests Suspected parapharyngeal abscess

CT of soft tissue of neck to determine extent of abscess Lateral soft tissue x-ray of neck Fig. 3.163  Diagnostic algorithm.

M A

A

A

B

Fig. 3.164  Computed tomography scan of parapharyngeal abscess in a 3-year-old child. (A) Sagittal section demonstrating parapharyngeal abscess (A) and mucosal swelling (M) in the maxillary sinus. (B) Coronal section of parapharyngeal abscess (A). (From Kliegman RM, Stanton B, St. Geme J, et al: Nelson textbook of pediatrics, ed 19, Philadelphia, 2011, Saunders.)

Section III n Diseases and Disorders

417

111.  Pelvic Mass (Fig. 3.165)

 

Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • Ultrasound of pelvis is best initial study (Fig. 3.166)

Best Test(s) • Biopsy of pelvic mass Ancillary Tests • CA 125 • CBC, creatinine • Serum hCG

Ancillary Tests • CT of pelvis with IV contrast • MRI of pelvis Pelvic mass on exam, negative pregnancy test Ultrasound of pelvis

Simple cyst (200 m

IIb

Pain-free, claudication walking 2.5 pmol/mL or metanephrines >1.4 pmol/mL indicate pheochromocytoma with 100% specificity)

Ancillary Tests • Scintigraphy with iodine-131- or 1-123-I- MIBG (100% sensitivity); this norepinephrine analog localizes in adrenergic tissue and is particularly useful in locating extraadrenal pheochromocytomas • 6[18F]-fluorodopamine PET (reserved for cases in which clinical symptoms and signs suggest pheochromocytoma and results of biochemical tests are positive but conventional imaging studies cannot locate tumor) aDiagnostic

Ancillary Tests • 24-h urine collection for metanephrines (elevated) • Clonidine suppression test

imaging is indicated only after biochemical diagnosis. 

Diagnostic

Elevated

Suspected pheochromocytoma

CT or MRI of adrenals

Scintigraphy with 131-I MIBG

Plasma-free metanephrines

Normal

Nondiagnostic

Elevated

Nondiagnostic

24-hr urine collection for metanephrines

PET scan

Normal Diagnosis unlikely

Fig. 3.171  Diagnostic algorithm.

Diagnostic

Section III n Diseases and Disorders

423

115.  Pituitary Adenoma (Fig. 3.172) Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • MRI of pituitary with gadolinium (Fig. 3.173)

Best Test(s) • Tests for hormonal excess or deficit based on clinical presentation (e.g., serum prolactin level, IGF-I, free T4, dexamethasone suppression test)

Ancillary Tests • CT of pituitary if MRI is contraindicated Comments Fig. 3.174 illustrates a radiologic classification of pituitary adenomas.

Ancillary Tests • None

  Diagnostic

Suspected pituitary adenoma

Lab tests for hormonal excess or deficit

MRI of pituitary with gadolinium Normal

Diagnosis unlikely

Fig. 3.172  Diagnostic algorithm.

A Pituitary tumor with suprasellar extension

B Fig. 3.173  Magnetic resonance imaging scan showing a large pituitary tumor with suprasellar extension causing acromegaly. (From Besser CM, Thorner MO: Comprehensive clinical endocrinology, ed 3, St. Louis, 2002, Mosby.)

424

Section III n Diseases and Disorders

Fig. 3.174  Radiologic classification of pituitary adenomas. Pituitary tumors are commonly classified on the basis of their size, invasion status, and growth patterns. Tumors less than or equal to 1 cm in diameter are designated microadenomas, whereas larger tumors are designated macroadenomas. Grade 0: Intrapituitary microadenoma; normal sellar appearance. Grade I: Intrapituitary microadenoma; focal bulging of sellar wall. Grade II: Intrasellar macroadenoma; diffusely enlarged sella; no invasion. Grade III: Macroadenoma; localized sellar invasion and/or destruction. Grade IV: Macroadenoma; extensive sellar invasion and/ or destruction. Tumors are further subclassified on the basis of their extrasellar extension, whether suprasellar or parasellar. (From Besser CM, Thorner MO: Comprehensive clinical endocrinology, ed 3, St. Louis, 2002, Mosby.)

Section III n Diseases and Disorders

425

116.  Pleural Effusion (Fig. 3.175) Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • Chest radiograph PA and lateral upright (Fig. 3.176) and lateral decubitus (Fig. 3.177)

Best Test(s) • Diagnostic thoracentesis and pleural fluid analysis for pH, LDH, glucose, cell count, protein. Light’s criteria are used to diagnose exudative vs. transudative effusion. An effusion is likely exudative if at least one of the following exists: 1. Pleural fluid protein/serum protein >0.5 2. Pleural fluid LDH/serum LDH >0.6 3. Pleural fluid LDH is more than twothirds normal serum LDH

Ancillary Tests • CT of chest without contrast • Ultrasound (if necessary) for diagnostic thoracentesis

Ancillary Tests • Serum total protein, albumin, LDH, glucose • CBC • Pleural biopsy • ADA • Cytologic analysis

 

Suspected pleural effusion

Chest x-ray (lateral and decubitus)

Diagnostic thoracentesis Ancillary labs

Elevated fluid protein (pleural fluid protein/serum protein >0.5), elevated LDH (pleural fluid LDH/ serum LDH >0.6)

Clear fluid, low protein, low LDH, normal glucose

Transudate Exudate Rule out CHF, nephrosis, cirrhosis, hypothyroidism, SLE

Bloody fluid

Normal/mild WBC elevation

High amylase level in fluid

Rule out neoplasm, PE, traumatic thoracentesis, trauma

Rule out uremia, RA (low glucose level)

Rule out pancreatitis or ruptured esophagus

CT of chest and pleural biopsy if suspecting neoplasm

Rule out empyema or parapneumonic effusion

Pleural fluid pH 40 U/L) and lymphocytic effusion

Rule out TB

Gram stain and cultures, AFB stain and cultures

426

Section III n Diseases and Disorders

A

B

Fig. 3.176  Moderate-sized pleural effusion. On this upright posteroanterior chest x-ray (A), blunting of the right costophrenic angle (arrows) is the result of pleural fluid. On the lateral view (B), fluid can be seen tracking up into the major fissure (black arrows), and blunting of the right posterior costophrenic angle is seen (white arrows). (From Mettler FA: Essentials of radiology, ed 3, Philadelphia, 2014, Saunders.)

A

B AP

PA

Supine

C

Down

D

Lateral

Upright

Decubitus

Fig. 3.177  The appearance of pleural effusions depending on patient position. On an upright posteroanterior chest x-ray (A), a large left pleural effusion obscures the left hemidiaphragm, the left costophrenic angle, and the left cardiac border. On a supine anteroposterior view (B), the fluid runs posteriorly, causing a diffuse opacity over the lower two-thirds of the left lung; the left hemidiaphragm remains obscured. This can easily mimic left lower lobe infiltrate or left lower lobe atelectasis. With a left lateral decubitus view (C), the left side of the patient is dependent, and the pleural effusion can be seen to be freely moving and layering (arrows) along the lateral chest wall. These findings are shown both diagrammatically and for a right pleural effusion (D). (From Mettler FA: Essentials of radiology, ed 3, Philadelphia, 2014, Saunders.)

Section III n Diseases and Disorders

427

117.  Polyarteritis Nodosa (Fig. 3.178) Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • Abdominal arteriogram (Fig. 3.179) or CT angiography: reveals small or large aneurysms and arteries’ focal constrictions between dilated segments, usually in renal, mesenteric, or hepatic arteries

Best Test(s) • Biopsy of small- or medium-sized artery (biopsies of gastrocnemius muscle and sural nerve are commonly performed when potential involvement is confirmed by abnormal nerve conduction studies)

Ancillary Tests • CT or ultrasound of abdomen to exclude other causes

Ancillary Tests • ESR, CBC • HBsAg, ANA • ALT, BUN, creatinine • p-ANCA

  Ancillary labs Suspected polyarteritis nodosa

Arteriography or CT angiography Biopsy of small or medium-sized artery

Fig. 3.178  Diagnostic algorithm.

Fig. 3.179  Aneurysms on the mesenteric artery in polyarteritis. (From Hochberg MC, Silman AJ, Smolen JS, et al: Rheumatology, ed 3, St. Louis, 2003, Mosby.)

428

Section III n Diseases and Disorders

118.  Polycythemia (Fig. 3.180) Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • None

Best Test(s) • Serum erythropoietin level (low) • Peripheral blood JAK2 V617 mutation screen

Ancillary Tests • Low-dose CT chest in patients with significant smoking history • CT or sonogram of kidneys when renal neoplasm suspected  

Ancillary Tests • Leukocyte alkaline phosphatase (increased), B12 level (increased), uric acid level (increased) • O2 saturation

Elevated Hb/Hct (Hct >54 in men, >49 in females), leukocytosis, thrombocytosis

Serum erythropoietin, JAK2 V617 mutation screen

Low erythropoietin level, positive JAK2 V617 mutation

Diagnosis of p. vera likely

Normal or high erythropoietin and negative JAK2 V617 mutation

Diagnosis of p. vera unlikely

Rule out erythropoietinproducing states (e.g., renal cell carcinoma, hepatocellular carcinoma, polycystic kidney disease), hypoxia, hemoglobin with high O2 affinity

Fig. 3.180  Diagnostic algorithm.

Section III n Diseases and Disorders

429

119.  Portal Vein Thrombosis (Fig. 3.181) Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • Doppler ultrasound of portal vein (Fig. 3.183)

Best Test(s) • None

Ancillary Tests • Abdominal CT (Fig. 3.182) with IV contrast (r/o neoplasm)

Ancillary Tests • CBC with differential • Coagulopathy screen (PT, PTT, factor V Leiden protein C, protein S, antithrombin III, lupus anticoagulant) • ALT, AST, creatinine, urinalysis • ANA

  Diagnostic Suspected portal vein thrombosis

Doppler ultrasound of portal vein Nondiagnostic

Ancillary lab tests

CT of abdomen

Diagnostic

Ancillary lab tests

Fig. 3.181  Diagnostic algorithm.

a

S

Fig. 3.182  Portal vein thrombosis. Postcontrast computed tomography shows a low-attenuation thrombus (arrowheads) filling and distending the right portal vein and branches. Collaterals have formed in the gastrohepatic ligament (arrow). The spleen (S) shows multiple infarctions. The splenic vein (not shown) was also thrombosed. Ascites (a) is present. (From Webb WR, Brant WE, Major NM: Fundamentals of body CT, ed 4, Philadelphia, 2015, Saunders.)

Section III n Diseases and Disorders

430

hypoechoic (normal) blood in portal vein

echogenic thrombus in main portal vein

A

flow is absent in main portal vein flow is present in inferior vena cava

B Fig. 3.183  Portal vein thrombosis: Ultrasound. This 22-year-old woman 2 months postpartum presented with 1 week of right upper quadrant pain. Ultrasound was performed to evaluate for suspected cholecystitis or symptomatic cholelithiasis. Instead, portal vein thrombosis was discovered. The postpartum state is a risk factor for this condition. Hypercoagulable states and inflammatory or neoplastic abdominal conditions, including pancreatitis and abdominal malignancies, also can result in portal vein thrombosis. A, Ultrasound grayscale image showing thrombus in the main portal vein. B, Doppler ultrasound showing no flow within the portal vein. (From Broder JS: Diagnostic imaging for the emergency physician, Philadelphia, 2011, Saunders.)

Section III n Diseases and Disorders

431

120.  Precocious Puberty (Fig. 3.184) Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • MRI of hypothalamic-pituitary region with gadolinium

Best Test(s) • LH, FSH • GnRH

Ancillary Tests • CT of hypothalamic-pituitary region if MRI is contraindicated • MRI or CT of adrenal glands • Ultrasound of testicle in patient with unilateral testicular swelling • Pelvic ultrasound in females

Ancillary Tests • hCG • Serum testosterone, estradiol • TSH • Adrenal androgens (DHEAS, D4 androstenedione) Comments Table 3.26 describes a protocol for investigation of precocious puberty.

 

Serum LH, FSH x 3

LH, FSH prepubertal

Serum testosterone, estradiol DHEAS, androstenedione

Elevated LH

Beta subunit of hCG to rule out gonadotropin-producing neoplasm

LH, FSH pubertal

Suspected precocious puberty

Elevated GnRH Normal/low

MRI of hypothalamic pituitary region with gadolinium GnRH-dependent precocious puberty (idiopathic, CNS tumors, post-head trauma, post-CNS infection) GnRH-independent precocious puberty (congenital abnormal hyperplasia, adrenocortical tumor, perirectal tumors)

Fig. 3.184  Diagnostic algorithm.

432

Section III n Diseases and Disorders

Table 3.26    Protocol for Investigation of Precocious Puberty History, family history Exposure to environmental sex steroids Physical examination

Cutaneous lesionsa (e.g., neurofibromatosis, McCune-Albright syndrome) CNS examination

Auxology

Pubertal staging (Tanner) Height, weight, height velocity Bone age

Hormone measurements

Testosterone/estradiol Luteinizing hormone/follicle-stimulating hormone Adrenal androgens (DHEA-S, androstenedione) 17-hydroxyprogesterone + ACTH stimulation test hCG-β Gonadotropin-releasing hormone test

Radiology

Pelvic ultrasound Magnetic resonance imaging of the hypothalamic-pituitary region

aDNA

analysis for known genetic disorders (testotoxicosis, McCune-Albright syndrome). ACTH, Adrenocorticotropic hormone; CNS, central nervous system; DHEA-S, dehydroepiandrosterone sulfate; hCG, human chorionic gonadotropin. From Besser CM, Thorner MO: Comprehensive clinical endocrinology, ed 3, St. Louis, 2002, Mosby.

Section III n Diseases and Disorders

433

121.  Proteinuria (Fig. 3.185) Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • None

Best Test(s) • 24-h urine protein collection

Ancillary Tests • Ultrasound of kidneys

Ancillary Tests • Serum glucose, BUN, creatinine • Urine protein IEP • ANA; serum C3, C4 • Serum c-ANCA, p-ANCA • Anti-GB membrane Ab • HBsAg, HCV, HIV • CBC

  ANA

Rule out SLE Rule out granulomatosis with polyangiitis

24-hr protein >3.5 g/day (nephrotic syndrome)

Urine protein 24-hr collection

Proteinuria

Abnormal proteins Serum glucose, BUN, creatinine

c-ANCA

Rule out viral etiology

HepBsAg, HCV, HIV

Rule out Goodpasture’s syndrome

Anti-GB membrane Ab

Rule out cryoglobulinemia, membranoproliferative GN

C3, C4

Rule out diabetic nephropathy

Urine protein IEP

Elevated glucose

DM, impaired glucose tolerance

Fig. 3.185  Diagnostic algorithm.

Rule out diabetic nephropathy

434

Section III n Diseases and Disorders

122.  Pruritus, Generalized (Fig. 3.186) Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • None

Best Test(s) • CBC with differential (Box 3.7)

Ancillary Tests • Chest radiograph • CT of abdomen and chest with IV contrast

Ancillary Tests • ESR (nonspecific) • FBS, BUN, creatinine • ALT, AST, alkaline phosphatase, bilirubin • TSH

  Rule out drug reaction Rule out dry skin Generalized pruritus

Rule out skin infection/ infestation (e.g., scabies) Rule out urticaria Normal skin exam

Normal

Rule out psychogenic pruritus

Abnormal labs

Further testing depending on lab abnormality (e.g., CT of abdomen if elevated LFTs); CT of chest and abdomen if lymphoma suspected

CBC with differential, ancillary labs

Fig. 3.186  Diagnostic algorithm.

Section III n Diseases and Disorders

BOX 3.7    Causes of Pruritus With, and Without, Skin Disease WITH SKIN DISEASE

Drugs, scabies, pediculosis, insect bites, parasites (roundworm) Eczema Contact dermatitis Urticaria Lichen planus Pityriasis rosea (“herald” patch) Dermatitis herpetiformis (gluten sensitivity)

WITHOUT SKIN DISEASE

Hepatobiliary—jaundice, including primary biliary cirrhosis Chronic renal failure Hematologic: • Lymphoma • Polycythemia rubra vera Endocrine: • Myxedema • Thyrotoxicosis Carcinoma: • Lung • Stomach Drugs

From Cameron P, et al: Textbook of adult emergency medicine, ed 5, Philadelphia, 2020, Elsevier.

435

436

Section III n Diseases and Disorders

123.  Pulmonary Embolism (Fig. 3.187, Table 3.27)

 

Diagnostic Imaging

Laboratory Evaluation

Best Test(s) • CT with IV contrast (Fig. 3.188) is best screening test to r/o PE in patients with baseline chest radiograph abnormalities

Best Test(s) • d-dimer by ELISA (normal d-dimer assay in patients with low probability of PE excludes diagnosis; normal d-dimer in patients with nondiagnostic lung scan, negative Doppler ultrasound of extremities, and low clinical suspicion excludes DVT)

Ancillary Tests • V/Q scan (when readily available, is useful as initial test in patients without baseline chest x-ray abnormalities) • Pulmonary angiography gold standard (but invasive and not readily available) • Compressive duplex ultrasonography of lower extremities (useful in patients with inconclusive lung scan or spiral CT and high clinical suspicion)

Ancillary Tests • Pulse oximetry, ABGs (decreased PaO2, PaCO2, elevated pH) • A-a oxygen gradient; measure of the difference in oxygen concentration between alveoli and arterial blood; a normal A-a gradient

Fig. 3.187  Integrated strategy for diagnosis of pulmonary embolism (PE) using clinical probability assessment, measurement of d-dimer, and computed tomography angiography (CTA) as the primary imaging test. Patients with low clinical probability (i.e., PE unlikely, negative d-dimer) need no further testing, but if d-dimer is positive, they should proceed to CTA, and if this is nondiagnostic, to ultrasonography of the legs. Then either treat or repeat the ultrasound in 1 week. Patients with high clinical probability (i.e., PE likely) need not have d-dimer measured but should proceed directly to CTA. If CTA is not diagnostic, options are to perform ultrasonography of the legs or proceed to pulmonary angiogram. If ultrasound of legs is negative, options are to repeat in 1 week or proceed to pulmonary angiography. (From Vincent JL, Abraham E, Moore FA, et al: Textbook of critical care, ed 6, Philadelphia, 2011, Saunders.)

Section III n Diseases and Disorders

437

Table 3.27    The Pulmonary Embolism Severity Index: Predictors of Low Prognostic Risk PREDICTOR

SCORE POINTS

Age, per year

Age, in years

Male sex

10

History of cancer

30

History of heart failure

10

History of chronic lung disease

10

Pulse ≥110/min

20

Systolic blood pressure